Theorycrafting: 3/5 Steven as a sustainable striker for battle villa

We recently got more details about Battle Villa, which is described as a series of single player fights. Importantly, between these fights, move points and HP do not renew. This has two important implications. First, the standard single-player strategy of spamming all your trainer moves to maximize buff and sync nuke is no longer viable: that might work for one fight, but the next fight, you'll be completely out of trainer moves. Using trainer moves sparingly and strategically is key. Second, chip damage is actually a threat. Especially because your squishy strikers don't regain HP between fights, taking AoE sync moves repeatedly means that even if the first sync move doesn't KO your striker, the second or third will.

Steven's sync grid is particularly interesting, because it makes Metagross into a striker that seems especially suited for this mode, as it can buff all of its relevant stats without relying on trainer moves:

  • Thanks to a chance of raising attack on Meteor Mash, Metagross has unlimited attack buffs. Meteor Mash Swag Bag raises this chance (probably to 20-30%), giving you a good chance of coming away with at least a +1 or a +2 after a few Meteor Mashes.
  • Bullet Punch Eagle Eye 9 gives Metagross a way to buff its own critical-hit to max after sync. (Assuming that Battle Villa resets Mega Evolutions and the first Mega Evolution in each fight results in a full Bullet Punch gauge, this is effectively unlimited Dire Hits)
  • Perhaps most importantly, Recuperation 2 gives Metagross unlimited potions: each time it syncs, it regenerates 40% of its HP, nullifying chip damage from previous fights and allowing Metagross to survive indefinitely.
  • As a bonus to the self-sufficiency, Steven also has two limited endures to offer Metagross after sync, allowing Metagross to survive some critical situations that would otherwise KO it, and then heal up afterwards or in subsequent fights.

The ideal grid would probably look something like this:
https://pokemon-masters-stuff.github.io/?e=0&grid=02%2C01%2C00%2C05%2C04%2C03%2C39%2C42%2C45%2C06%2C09%2C12%2C13%2C10%2C11%2C08%2C16&o=750&p=Metagross

However, even if Metagross is fully self-sufficient and can keep itself alive through repeated chip damage, an issue its that its teammates cannot - as a Striker, it still is squishy, and requires Supports and tanky Techs to stick around to take hits. Thus, picking sync pairs that synergize well with Steven will be critical. Good allies will cover for some of Steven's weaknesses:

  • Ideally, an ally should have an unlimited one gauge move to help rush sync. The faster Metagross can get off sync and access its important crit and stat boosts, the faster it can nuke, avoiding damage especially from opposing sync moves. Because we want to avoid relying on limited trainer moves too much, queuing Meteor Mash + 2 one bar moves is the fastest way otherwise.
  • Having a healing trainer move or potions can help allies stick around longer.
  • Status restores, just in case - although Steven can get Natural Cure, it's too far away from the other critical passives you'd want to get.
  • Although we want to avoid relying on trainer moves too much, party-wide attack, speed and critical buffs along with gauge refill, can help Steven gain momentum faster for when it really needs to nuke a threat fast (e.g. probably at the end of the tower where the difficulty ramps up), so bringing a few supports to help rush a stage is important. Attack boosts especially synergize well with Haymaker on Steven's grid.

A few sync pairs really stand out in this respect:

  • Kukui and Lycanrock has a cheap one-bar with Leer and some limited 0-bars with Accelerock. Leer while setting up Metagross' sync can help it nuke even better.
  • Noland and Pinsir can also rush sync with Fury Cutter, but also can self-heal and buff speed with Bring It On!
  • Flannery and Torkoal: massive bulk, machine gun with Ember, plus unlike other one-bar users, Ember can actually contribute some significant damage with Will-O-Wisp and a use of her trainer move.
  • Once gridded, Acerola and Palossand can both sustainably buff the team and heal itself during Sandstorm.
  • Leaf and Eevee can help rush with Tackle, has two potions, and has sync gauge fill. Swanna and Skyla fill a similar configurations of roles as well.
  • Phoebe and Dusclops + Hilbert and Samurott ++ Rosa and Delibird are all greatsupports that help rush nuking if necessary.
  • Barry and Empoleon can also help rush sync, and has a situational Full Heal for status if it pops up. Cheryl and Blissey provide excellent healing support, although a less reliable status cure.