Well I made this team a couple of weeks ago and posted it in the bazaar so going to just copy the post from there
My recent meta discussion post included a small builder dump that I'll do that below in a spoiler for anyone who uses this thread for teams. I'm not going to comment on them, but feel free to send me a message here or on discord if you have any questions about them. Onwards to the main reason for this post...
Mola Giratina-O Balance
Team Origins
After my participation in Trios ended I still had a pretty strong urge to build some new stuff. The metagame is still rife for development and I had a lot of ideas for teams that were skeletons with a name in my builder. Adem has spent the last couple of weeks praising various CM Refresh Arceus formes and they are something I've been meaning to give another go for a while. The last time I'd attempted to build with them was in the Xerneas metagame where any deviance from 'standard' stuff was more often than not harshly punished. CM Refresh Arceus-Dark was certainly usable during that time, but everytime I built around it, the results left me unsatisfied. I either struggled to pilot them in game or the teams had consistency issues with certain matchups that I felt unacceptably large.
I had a lot of ideas for my Trios game vs R8 that were skeletons with a name. They have six mons, but at most two of them even have complete sets if that. I fiddled around with them, but found myself spinning aimlessly in progressing past the concept stage. That wasn't the case with CM Refresh Arceus-Dark and this is the result.
My starting elo was around 1680ish and the team went 29-2. The first loss was the first game with the team where I was very quickly reminded that Alomomola's default ability is Healer not Regenerator. This is not the first time forgotten this, but it will hopefully be the last. The other loss was largely due to Pokemon being Pokemon. Most mons in this tier rely on moves that are not 100% accurate and sometimes that really screws you over. Though it wasn't the only game with a lot of hax, it was fortunately was the only one where the result was influenced.
If I change anything on this team i'll update this post, but those changes are likely to be minor. The only likely changes are optimizing Giratina-O's EVs and maybe shifting some over to Def on Arceus-Dark. I didn't spend a huge amount of time on this team, but that is just the way she goes. Sometimes things just work.
Pokemon / Roles
I've said before that with nearly every team I make I just insert defensive Overheat Primal Groudon as the first slot in the builder and change it later if needed. That was indeed the case with this team though I have been
experimenting with other sets recently. Unfortunately this team cannot afford that set. The team needs hazards somewhere and well Primal Groudon is a damn good rocker.
Primal Groudon does not need to, nor does it benefit from being played aggressively on this team. Against more offensive teams it can be difficult to safely Wish-pass to and is better off preserving HP. Against everything else it can be played somewhat freely, but should be played more safely as to not get worn down by Toxic. Alomomola generally keeps it healthy enough to be a decent offensive Primal Kyogre check if Wish is used aggressively.
My teambuilding ethos has always been if your team consistently requires hazards to be removed more than three times the team probably works better with Yveltal or Ho-Oh, Alomomola changes that. Alo+ Giratina-O is something I've been meaning to build with for a while, but have only just gotten around to now.
First, the EVs are wholly unoptimized. I put enough speed for base Zygarde, maxed HP, and dumped the rest into SpA. I'll revisit them in the future as I'm sure some investment into Def/SpD is probably better than what I have currently. Anyone that uses Giratina-O is very familiar with how meticulously its HP has to be managed at times. That obviously goes out the window (slight exaggeration) when Alo can Wish pass. Even if Primal Groudon switches in to block Flip Turn Alo is going to be fully healthy and can just Wish again directly to Giratina-O.
I've gone with Thunder Wave on this team as the status move of choice. Nothing that can absorb a Thunder Wave really wants to switch into Giratina-O. Primal Groudon and Zygarde does as well pre Tera. Arceus-Ground can absorb it, but is forced to recover afterwards when Giratina-O would switch out anyways. Tera Poison is chosen over Tera Steel because the team already is somewhat weak to Zacian-C and this provides a resistance to Tera Fight CC while covering for the TB Ground sets that delete Primal Groudon. +3 Behemoth Blade still OHKOes which I forgot about v BananaTimeZ.
All in all, this team has been a great first experience w/ Alo + Giratina-O. Though I do really quite like it, I'm having trouble imagining a team structure that deviates too far from this one without becoming incredibly passive while remaining somewhat consistent.
All Alomomolas must be named after R8 in some way or you risk unleashing the wrath of Big Stall for not giving the proper credit. Alo is the main pivot and status absorber. Physdef was a consideration as the team does have some issues with Zacian-C, but being able to pivot more reliably makes the team significantly more consistent. The Zacian-C matchup is not great, but it is managable enough that the trade-off is worth it. I'm just noticing now that it is Tera Dark and that should probably be changed. I didn't put much thought into it and havn't had the desire to tera it once. When the team is edited I'll probably change it Poison or Fire. There isn't really much to say here, Alo really just does Alo things.
The teams catch all physical check. It isn't replaceable as the team becomes far too weak to Double Dance Primal Groudon and Marshadow without it. It is also the emergency Zacian-C check. R8 suggested making it faster than Zacian-C after a para and I get where that is coming from but Zygarde is already barely hanging on v Double Dance Primal Groudon and Zacian-C itself and glaring either of them means Giratina-O can dispatch them with Hex with some minor chip. Similar to Alo there isn't really much to talk about. This is the standard Zygarde set that does standard Zygarde things. The only thing lacking is the nickname, but I've built a lot of teams with Zygarde recently and scraped the bottom of the barrel for something.
The mon that the team is built around. Due to Adem raving about it so much the nickname felt appropriate. CM Refresh Arceus-Dark has impressed me. It isn't as good as the standard defensive set, but it is better than I gave it credit for. The defensive set is still better, but CM Refresh is very good. The single caveat is that I can't imagine using this without Zygarde. The defensive set does function well enough as a self sufficient defensive wall, but this set does not. Having to pair it with Zygarde isn't a big issue and the issues I had with CM Refresh Arceus-Dark were likely remnants from trying to build with it during the Xerneas metagame.
I've gone with a Timid SpD spread on Arceus-Dark primarily for LO Yveltal. This is the spread I use on Arceus-Fairy for the same purpose. LO Yveltal is incredibly common and the extra SpD goes a long way towards saving recovers which often ends up being quite important. Saving these recovers enables Arceus-Dark to more easily set up a sweep v things like Eternatus, LO Yveltal itself, and utility Arceus formes late game. The Timid nature also makes a huge difference as it lets Arceus-Dark set up on LO Yveltal as it CM and Recover as the Taunt wears off if needed. This is something that comes into play frequently.
Tera Fairy was chosen for a few reasons. First, the team has 3 dragons on it so being able to absorb attacks for them if needed is nice. It never terad for this reason, but the ability to do so if needed was quite nice. Second, it maintained a Dark resist so it can still handle LO Yveltal defensively. Third, it prevents Dragon Tail from interrupting setup if needed. Fourth, it enables Arceus-Dark to win against a Marshadow that has locked itself into Low Kick and allows Arceus-Dark to scout it in a pinch if Mola has been KO'd. It also gets rid of the Fairy weakness v Arceus-Fairy, but the only one I faced where this would have mattered was a faster set with Taunt which shut it down anyways.
Before testing I went in with the expectation that Arceus-Dark would be the primary wincon, but more often than not Eternatus or Zygarde would be. Arceus-Dark could have won in some of these games but I don't see the point in extending the game to show it doing so.
Credit to 09-10a for the set. It is one I like a lot and have been using a fair amount recently. Eternatus was the last mon to be put on the team and one that I thought might change. I was looking for a faster offensive mon that had a decent matchup into stall. The latter was particularly important as the first five can win vs stall, but using Zacian-C or Marshadow would leave less margin for error than I am comfortable with against stall. I decided to slap this Eternatus set on and change it up if the HO matchup turned out to be too rough.
Though I love Recover Meteor Beam Eternatus, it is not something that should be slapped on a team without any thought. Recover is great on this set, but dropping either Fire Blast or Sludge Bomb means Eternatus is always going to be walled by Zacian-C or Arceus-Fairy. Given the rest of the team I went with Fire Blast. This turned out to be the right decision and Arceus-Fairy, utility sets at least are fairly managable. Tera Fairy is again useful because of the whole 3 Dragons thing, but it also makes Eternatus Ditto proof which can be an issue for the standard Meteor Beam set.
Threats
It is reasonably managable, but it can threaten to break some big holes or potentially sweep. It really depends on the specific set and gamestate. Zygarde can glare and live any +3 hit from full. At this point Giratina-O should be able to revenge it with Hex. Primal Groudon deals with non TB Ground sets. The sets the team runs into the biggest issues with are bad ones, but ladder is ladder. Really the only mon that Zacian-C enters for free on is Arceus-Dark. Even then tanking a judgement puts it in range of Hex.
Applies to most Arceus formes but really any Arceus forme faster than Arceus-Dark with Taunt is annoying. As shown in one of the replays Eternatus can get past faster utility sets. Never ran into a faster CM set but I'd imagine that probably isn't great to deal with. It really depends on the actual set and the team that it is on. It isn't a 6-0 or anything but depending on the set and gamestate it can probably sweep fairly easily.
Never ran into this but I doubt the team handles Spore sets particularly well. Nuzzle is fine.
Replays
:sv/primal-groudon: 
:sv/giratina-o: 
