I've seen a lot of Forretress slander recently so I'm gonna try to make a post explaining how I make it work if people wanna try it for themselves, because I believe the Ball is still viable.
So obviously the main trait of Forretress is being a Spikes user that is immune to Sand, which gives it longetivity. Then you have to ask yourself, why would I use Forretress when I can use Skarmory, which is a lot more flexible because it doesn't die to every Fire move, and it is immune to Spikes which means it makes better use of Leftovers recovery.
The first and most obvious thing that comes to mind is: "Forretress is very good into other Skarmory thanks to Spin, especially ProTox on which you sit on forever." You'd be right, but if it was that easy, Forretress would be more popular.
Why Forretress "sucks"
- Forretress doesn't work like Skarmory
You cannot use Forretress like Skarmory. Every damage Forretress takes may stick, because it is grounded unlike Skarmory, that's the first big thing you have to understand. Which means that it's harder to get more than one Spikes, and it is also harder to get Spikes back if your opponent spins in the meantime, unlike a Skarmory which can pivot into ground moves, or comes on Claydol all day to replenish its health with Leftovers (or Forry itself).
- Forretress is an awkward Spinner
We did mention earlier that Forretress dream match-up is facing ProTox Skarm without a Ghost type, because then you completely blank the Skarm and its spikes all day. And while yes, it will happen once in a while, no it won't be a common occurence. A lot of Skarmory run Drill Peck and will actually pressure the Forretress until they find an opening to get one spikes up, which allows them to pressure any Forry team, and makes it harder for Forry to spin later. Add to that working around a potential back Gengar

, Forretress being slower than most Pokemon in general and getting weakened in the process and you quickly understand while using Forre that damn, that Pokemon is a bad spinner, and it has to Spikes too???
- Skarmory can still dominate you
One big problem of common Forry sets, which people believe to be Spikes/Spin +2 of HPBug/Earthquake/Counter/Explosion is that they don't damage Skarmory at all. We already mentionned why DP Skarmory is an issue in the previous paragraph but one problem is that Skarmory is actually free heal on Forretress. Unless you're facing the teams that run ProTox without a Ghost or any Wallbreaker, the standstill is often bad for the Forry user, as either Skarm eventually beats you down with DP, or use Skarm into Wallbreaker to abuse Forretress and create openings (unless your Forry team magically hardwalls the Skarm team, which rarely happens.
Why use Forretress then?
While most people would think it's because it Spins, Forretress two other benefits is a more direct offensive presence through Boom, and the ability to directly threaten and weaken Spinners (Starmie

& Claydol

) thanks to a stabbed HP Bug. Another benefit is that Forretress isn't removed as easily by Magneton, as Modest MaxSpa only kills 30% of the time, while you can kill back with Counter/EQ).
How to circumvent the aforementionned issues
- Use Forretress cautiously
If you wanna make good use of Forretress, you will want to click more than Spikes once throughout the game. But like we said earlier, Forretress is slow, and takes Spikes damage, which means a
Forretress belows ~40% become extremely hard to get use of. Only use Spikes once against Pokémons that can't bring you down and then leave the field to control the situation. Pokémons that will let you accomplish this are Swampert

, Blissey

, Zapdos

, Metagross

, Skarmory

, Claydol

, Suicune

, Milotic

, etc. You should ideally pivot Forretress on a weak move (for example Pert IB) so you don't take a Stabbed hit as you switch and then another as you spikes. Also avoid status if possible, just like you'd do with Skarmory, except it's even worse with Forretress.
- Give Forretress the right support
While most people know that one obvious support of Forretress is a Pursuit Pokémon for Gengar, they only think of helping it Spin. I'd say that Forretress actually crucially relies on Wish to work effectively, if not a side Spin or Leech Seed. Forretress needs help to get back to shape and continuously Spikes (and Spin?) throughout the game.
- Wish: Wish allows you to switch Forretress back in the game and get more Spikes or Spin more effectively. I strongly recommend Jirachi
and Bliss
partnership as they're the best suited to keep the Ball afloat.
- Rapid Spin: One of the shortcoming of Forretress is being pretty hard to use if Spikes get up, how about you use a more reliable Spinner then? Claydol
in particular will allow you to clear the field throughout the game, giving Forretress an easier time coming in and out, including with Wishes. You may also make better use of Forry's Lefties by doubling in and out. Finally, not using Rapid Spin on a Forretress frees another offensive moveslot to target even more Pokémons.
- Pursuit: If you're spinning with Forretress, this one is obvious as you will want to remove or severely weaken Gengar. Tyranitar
is your best guy, but technically Umbreon
can fit Forry teams quite well.
- Phazer or FastMon: unlike Skarmory, Forretress doesn't have a built-in phazing move, and while Boom will do the trick in some situations to prevent a set-upper abusing you, if you wanna keep Forretress around, make sure to pack a Phazer like Swampert or Zapdos, or a fastmon like Aero or MixMence to prevent any abuse from your opponent.
- Leech Seed: Leech Seed can passively heal and create situations where your opponent is forced to swich, use those at your advantage to heal Forry either through Seed or Leftovers from the free switch.
- Give yourself the edge vs Skarmory
We've talked earlier that DP Skarmory may beat you down, so let's reverse the situation:
- HP Fire: HP Fire allows you weaken Skarmory as it tries to wear you down. You're now also doing the same thing. It can also finish off a Gengar after it takes a Pursuit from your Tyranitar. You're now lacking a good damaging move into Starmie/Claydol so keep it in mind! For that matter, you should avoid Forretress that cannot touch Gengar
at all, as those are often EVd to tank Pursuit from Tyranit and WILL be a pain even at 8% if your Forretress can't finish them off.
- Zap Cannon: Zap Cannon, even with its shit accuracy, allows you effectively threaten Skarmory and Gengar from fucking with you. A Paralyzed Skarmory is immense for the Forry match-up, and it will give you breathing room to Spin/Spikes/heal from Leftovers. It also discourages Gengar from mindlessly coming in.
- Knock Off or Thief: pairing Forretress with a Pokemon that can remove Skarmory's Leftovers means that your HP Bug, Rapid Spin and Counter (into DP) now actually kill the Skarmory and give you the upperhand longterm.
Conclusions, and explorations
A Forretress team should think about making use of either its ability to directly combat Spinners, or its role compression as a Spiker/Spinner. Those teams will usually have a strong defensive presence to take advantage of Forry's strenghts. I suspect more Offensive Forretress teams are possible, in which case you could want to use HP Ghost Forretress to effectively weaken Gengar yourself, Boom to target Claydol/Starmie and even Speed EVs to get clutch Spins/Booms on a lot of Pokémons hanging betweene 136 and 180 speed. I suggest you still use max SpDef on those sets to tank about any non-Fire move.
Core Examples




Wish Rachi heals Forry and Dol. Dol spins for Forry, enabling you to use more offensive coverage, Milotic covers Mixed attackers alongside Jirachi. Milotic and Jirachi appreciate Spikes & Spin to work efficiently.




Same as above but with Celebi for Leech Seed and better Suicune answer than Milotic.




Same as above but with SpDef Zap to handle Mixed Attackers with better and aggressively use Spikes.
Note: Even if you have Claydol, Pursuit Tyranitar is still encouraged on those cores to really lock down every hazards match-up.



Suit Ttar + HP Fire Forretress can outlast all Skarmory, including partership with Claydol or Gengar. SpDef Zapdos handles some setuppers and mixed attackers while making use of Spikes.



Tyranitar Pursuits Gengar for Forry & Hariyama. Hariyama removes Skarmory Leftovers which allows Spin Forre to beat it longterm.
Replays
https://replay.pokemonshowdown.com/gen3ou-1515771692-ug488rzjjm62qwg0obck3r0tjvemyswpw
Forry gets one Spikes and Spin while Zapdos/Pert handles set-uppers, DDMence finishes the job.
https://replay.pokemonshowdown.com/smogtours-gen3ou-537192
Forry actively trades with an early Meta. Dying isn't an issue even with a back Skarmory thanks to Jira+Dol.
https://replay.pokemonshowdown.com/smogtours-gen3ou-538642
Dream Forry match-up where the field is entirely controlled against another Fat team.
https://replay.pokemonshowdown.com/smogtours-gen3ou-551783
FireForry prevents Skarmory from healing and becoming an issue again in the late game, only limiting it to one Spikes.