Some pre-release thoughts on Ogerpon from what I have seen so far. (I was typing this before it went live, soooooo....)
General Thoughts on Ogerpon
Stats: 80/120/84/60/96/110 (HP/Atk/Def/SpA/SpD/Spe)
BST: 550
(Funnily enough, this mon has 5 less BST than the three poison goons)
All forms share a Grass typing unless Terastalized.
This is definitely a mon with very defined strengths and weaknesses. While its offensive stats is not out-of-this-world (it is directly worse than Sneasler's 130 Atk + 120 Spe), it is very much serviceable. Its bulk is overall also decent for an offensive mon. It will not take super effective damage very well, but it can semi-reliability soak up neutral damage. It stat-spread overall is very solid but far from amazing.
All forms are coming with the Grass typing.
When it comes to offensive Grass typing, we only really have Meowscarada, Breloom, Rillaboom, and Brute Bonnet to its name, the latter two not being an OU caliber Pokemon in gen 9 (at least pre-DLC1 Boom is not OU caliber).
It has powerful offensive Grass moves in its disposal: between Ivy Cudgel (which serves as its secondary STAB in other forms), Wood Hammer (strongest Grass STAB), and Horn Leech. Power Whip also exists, but its low accuracy may make it an unattractive choice. Solar Blade can be used for Sun teams, especially with Heartflame form.
It has some good setup tools in Growth (especially good with Heartflame under Sun), Swords Dance, and Substitute.
It also has some good offensive coverage between Knock Off, Superpower, Low Kick, Play Rough, Zen Headbutt, and Stomping Tantrum.
It also possesses some good utility options in the form of (again) Knock Off, U-turn, Leech Seed, Spikes, Spiky Shield, Synthesis, and Taunt.
While all these options are all great, an immediate weakness I noticed is that without Tera and assuming a different form (
a problem I go over in more detail in the Teal Mask section), Ogerpon doesn't really do anything significant that stands out in comparison to its offensive Grass type competition: Meow has the highest speed + secondary STAB + Protean; Breloom having the highest attack of the three + priority STAB Fighting move + access to Spore; Boom having higher overall power and physical bulk + Grassy Terrain + now having a decently strong priority grass move. Its speed tier is also pretty awkward, with base 110 being woefully slower than a lot of other prominent offensive mons, although it is faster than certain other fast offensive mons like Enamorus and Wake.
That being said, lets talk about its interaction with Tera which does make it stand out.
It allows access to its secondary ability in boosting a specific stat, and this gets reapplied whenever you switch out (likely done cause you need to Tera to access this, thus it has opportunity cost). It of course have the basic benefits of Tera; getting an adaptability boost on one of its typings. The boost being permanent and potentially strong under certain circumstances means that the mon Tera'd does have a potential lasting impact on the battlefield.
It does have some notable downsides: a unique one in that its Tera is set and doesn't have any option of mixing it up, and said set type is one of the ones it already has. This makes its Tera options the most linear out of any mon in the game, which limits how flexible the mon can be both offensively and especially defensively. The fact that this mon needs to Tera in order to access its strong abilities means that you are encouraged to not Tera your other mons in your team in order to enable said abilities for Ogerpon.
Now lets go over each of the individual forms.
1.
Teal Mask
Held Item: None (Free item slot)
Type: Grass
Ability: Defiant / Embody Aspect 1 (+1 Speed)
This was a form that I was initially not too optimistic for when looking at it prior to more info coming out. If this form was stuck holding a mask item without the freedom to switch items, then this form would be very mediocre and close-to-no reason to use it over Meowscarada.
Fortunately, we live in a timeline where it does have freedom on which item it holds, which does change the game for it, although it still has some of the same growing pains I theorycrafted beforehand. The ability to hold any item means that Teal Mask can afford to run leftovers or HDB for more defensive sets revolving around Leech Seed + Horn Leech + Spikes. It also means that it can achieve a potentially nasty combo: Choice Band + Tera speed boost; or Swords Dance + Tera speed boost + other items like HDB. Grass STAB is very strong with this mon, possessing very high STABs in Wood Hammer, Power Whip, or Ivy Cudgel. It doesn't hit as hard as Boom does with Wood Hammer, but it is still very strong while also having a pretty good speed tier. Its offensive coverage, while not amazing, is still very solid between Superpower, Knock Off, Zen Headbutt, and Play Rough.
It also possesses a very fast U-turn, which is nice given that the Tera boost is +1 speed and doesn't go away upon switching, meaning that this can potentially have the fastest non-locked U-turn in the game. Hoopa-U in suicide watch as we speak.
Its base ability in Defiant is also very solid, allowing it option to punish Defog attempts from the opponent, although it cannot really threaten most users of Defog back. The note about not threatening Defog users does highlight a major issue with this form: it doesn't have a real way to threaten Flying types. All it has is Leech Seed and weak Rock Tomb to pose any threat to them (granted that Tomb is pretty good for particularly Moltres), and no secondary STAB to work with. Mons like Zapdos will be a massive problem to this form as a result.
In general, this is the form that suffers the most from not standing out in comparison to other offensive Grass type competition without using Tera on it.
For starters, mono Grass doesn't do this mon much of any favors. At least Rillaboom is stronger off the bat, more physically bulky, has Bulk Up in addition to also having Swords Dance, summons Grassy Terrain, and has access to a decently strong priority Grass move (not gen 8 level, but still solid). Oger does have a significant speed advantage, meaning that it is more immediately threatening to mons that outspeed Boom and isn't threatened by nerfed-Grassy Glide, so it does have that going for it. But still, without the immense team support Boom provides, possessing a mono-Grass typing with no real way to deal with Flying types becomes a massive problem, especially when not Tera'd. This also opens up Meow also being massive competition for it, thanks to its much higher speed tier, secondary STAB, Protean, also having Spikes + U-turn + Knock Off, and while it is weaker than Ogerpon, its attack is serviceable enough to threaten opposing mons.
A notable thing about this form is that even with how powerful the +1 speed boost + not being item restricted is, its Tera form also has a very notable issue: it is the form suffers the most from having no variety in its Tera type. It being permanently locked to mono-Grass for its entire existence does not do it much favors offensively or especially defensively. Setup sweepers in gen 9 loves to Tera off of their standard typing to get the jump on potential counters, or switch to a better defensive typing that facilitates the bulky role, but Ogerpon uniquely cannot do either, which further exacerbates it's Flying type problems.
One final thing to note is that the defensive sets has even more competition. As mentioned earlier, Boom is more physically bulky and has passive recovery with Grassy Terrain, plus can afford to run Bulk Up to make use of its higher physical bulk. This form could function as a fast lead slot option against opposing teams, but this one has harsh competition from Meowscarada, who is naturally faster without any need to Tera and has pretty much all of Ogerpon's support moves + STAB Knock Off. It also has harsh competition in the lead role from, funnily enough, Ogerpon's own Cornerstone form.
Summary:
This form has some potential mainly leaning to the +1 speed boost upon Tera and having a free item slot, potentially opening the door to some powerful combinations. However, this form possesses glaring flaws none of the other forms possess, mainly stemming from its problems threatening Flying types and its mono-Grass typing. It is also the form that stresses the usage of Tera the most in order for it to be not directly outclassed by other Grass type competition, which will limit its usage even further, and I am not sure if this mon is good enough even with Tera to work in a team that revolves around it being the sole Tera user.
2.
Wellspring Mask
Held Item: Wellspring Mask
Type: Grass/Water
Ability: Water Absorb / Embody Aspect 2 (+1 Special Defense)
Probably the form I have the biggest question marks about, but this one seems interesting. Grass/Water is a rare typing notably seen with Ludicolo, and provides some pretty good defensive profiles. While +1 SpD on Tera isn't anything noteworthy, it is the form that suffers the least from the linear Tera typing, as mono-Water is a popular and pretty good Tera type to become anyways.
Its base ability being Water Absorb is a very funny move by GameFreak considering that the mon already quad resists the type, but at least it means that it is not getting Scald burned anytime soon pre-Tera. It is a nice mon in that while it definitely benefits at times from being a mono-Water type defensively, but it isn't in any dire need to Tera this mon since its defensive typing is solid as it is. It also possesses some defensive traits to go alongside its defensive typing, between Horn Leech + Synthesis + Leech Seed for lots of recovery on its part, although having no item slot for Leftovers or Boots means that it is very liable in getting worn down. Its bulk is decent, but not out of this world good, so this form is very solid, albeit flawed defensively.
Summary:
Not really much else to say for this form: it is definitely the most well-rounded of the Ogerpon forms, not having the polarizing highs and lows of Teal and Heartflame. It is a mon worth considering if your team desperately needs an answer for a rain team, cause this mon kinda memes on them once Tera'd. Don't know if this equates to actual OU usage (I personally doubt it), but I can see a niche here. This form could also be potentially used in Ubers to meme on Kyogre as well.
3.
Heartflame Mask
Held Item: Heartflame Mask
Type: Grass/Fire
Ability: Mold Breaker / Embody Aspect 3 (+1 Attack)
Prior to the launch of this thread and the arguments brought up, this was the most exciting one for me. Grass/Fire is a brand new type combination introduced in this gen with Scovillian, and similar to the aforementioned mon and fellow offensive Grass type Brute Bonnett, this mon will definitely hit its stride in Sun teams. It also has some defensive synergy with some other prevalent offensive mons.
Mold Breaker is a pretty good ability for an offensive mon, meaning that the mon's Fire STAB (Ivy Cudgel) will hit past Flash Fire and its moves in general will hit past Unaware. Once you put this mon under Sun and Tera it, then things become exciting: the +1 attack boost helps mitigate the lack of a boosting item, and its Fire STAB becomes nuclear when boosted by Sun, by adaptability-esque STAB Tera Fire, and by +1 attack. While not a Chlorophyll or Protosynthesis boosted mon like Venusaur and Brute Bonnet before it, it is still very fast given the other Sun abusers without this ability (or not Proto speed boosted). This is a very damaging new addition to Sun teams.
That being said, this mon does have very glaring flaws: it is easily the form that suffers the most by not having an item. While it is fast and have set-up for days, base 120 attack with zero items does feel weak without the Tera +1 attack boost and/or Sun support. The Sun support thing is, of course, not too bad considering that Walking Wake Sun cores will remain a prevalent team style, but it is currently unknown how well this mon will fit in said already established cores in the long run. Either way, being mostly restricted to Sun teams and being a Tera hog on your team will inherently limit its usage. That being said, this mon being a Tera hog isn't as bad of a problem as with Teal form, as having gen 8 Intrepid Sword upon Tera'ing can never be a bad thing to do, but it is something noteworthy, especially since......
......the main glaring flaw of this form is that is the mon most weak to hazards in the generation. Because it cannot hold an item and that it will be a Fire type no matter if it is Tera'd or not, it means that it is exceptionably very weak to Stealth Rock with zero way to mitigate this, meaning that it will require more team support than most mons in the game. You cannot afford to slap HDB to fix this mon's Stealth Rock weakness cause... it can't. This isn't an insurmountable condition to fill by any means, but it is again another strain in the builder.
Summary:
It is funny Sun sweeper #12, although it does have a lot of merit in comparison to most of its competition, especially having gen 8 Intrepid Sword as its ability upon using Tera. Being mainly reliant on Tera and/or Sun will overall limit its usage in the long run, and its lack of holdable items while being Stealth Rock weak regardless of Tera will mean that it will require more team support than the average Sun sweeper. A Heartflame put in the ideal position is indeed strong if achieved. I feel that this form has potential to be an OU caliber threat, but I feel that this is very meta dependent and dependent how much its glaring flaws will end up holding it back in the long run.
4.
Cornerstone Mask
Held Item: Cornerstone Mask
Type: Grass/Rock
Ability: Sturdy / Embody Aspect 4 (+1 Defense)
Teal Mask Ogerpons got tired of seeing Flying types, so it instead dons the Cornerstone Mask to meme on them. This is the first time we have an offensive mon with the Cradily type combo, and it has some interesting results. The typing has merit and also some harsh pains defensively, having solid resists of Normal and Electric, but also notably being weak Steel, Fighting, Ice, and U-turn. Between that and no items, it is a very mixed bag in terms of defensive and offensive utility for a team. Being a Grass type that is fast, self-recovery, and doesn't fear Flying types are all very nice traits, but it cannot take much hits at all in turn, and the type combo not resisting much of the metagame can come back to wear it down further as a result.
This mon's relationship with its Tera ability is funny, cause I actually like the mon better with no Tera. It is because for the role I think it fits it best benefits better with Sturdy (which is explained in the paragraph below), but also +1 Defense boost (gen 8 Dauntless Shield) and the change to mono-Rock are both...... not great. Not worth using this mons Tera over someone better in your team except for the most niche of situations. I have seen someone in the thread mention Tera'ing the mon in the Sand for the funny +1 Defense + Rock type SpD boost. It is fire tech, but obviously nothing worth using seriously, especially since Sand is easily the worst weather in gen 9 rn. If you want funny stuff with mono-Rock Sandstorm, then you would use Garg instead.
Where I think this mon will shine is the lead role: it is a fast mon with Spikes, Encore, Taunt, Leech Seed, and Knock Off. With Sturdy, it is ensured that the mon will always live one hit from the opposing lead role. Rock typing also ensures that it eats Stealth Rocks on switch-in, although again the lack of item does limit how often it can come in. Main threat to this would be lead Meow carrying Taunt, but otherwise there isn't much stopping this mon from doing something in the lead.
In that regard, I actually do think this mon has a niche in the lead role that can potentially go side-by-side with Meow for the lead role that can threaten Flying types with potent Rock STAB (that doesn't miss all the time yippee!), more bulk to work with, and more access to recovery. To compensate, the mon does have lower speed than Meow, no STAB on Knock Off, no Protean, and no held item to work with.
Summary:
Unironically the best chance Ogerpon has to be a legitimate OU mon imo: this form can function as a solid lead mon that has different role from lead Meowscarada; namely its ability to threaten prevalent Flying types with Rock STAB. It of course has its downsides, mainly stemming from its typing and lack of a held item, and said traits also makes it not very good for being a general all-purpose offensive mon outside of the lead position. Probably the Ogerpon mon that benefits the least from its Tera gimmick, but at least that means you can afford to Tera other mons in the team more easily.
Overall summary:
Each form of Ogerpon seems to possess a well defined niche; Grass form for being a Tera sweeper, Fire form for being a Tera and/or Sun sweeper, Water form for laughing at Rain teams alongside a solid defensive typing, and Rock form for being a well-defined lead mon that separates from Meow. Each does have their very defined weaknesses though, mainly stemming from its stats being only good (not amazing), the Grass form being very Tera reliant to not be hilariously outclassed, the Fire form also being a massive Tera hog with a Stealth Rock weakness, all the Mask forms having no item to work with, and all of them having zero flexibility with Tera types. Rock form has the greatest chance of being legitimately OU, and maybe Fire depending on how the meta shapes up, but all of them seem to be lower tiered threats. That being said, each of them has very real potential to at least have a usable niche in the OU tier, with Water form potentially even having the slightest niche in Ubers, which is all very cool to see.
This mon is a nice change of pace. Last time we had a DLC legendary Pokemon with a low 550 BST, it was able to punch through Protect + Bulk Up + Swords Dance + CC + auto-crit secondary STAB.