Corrosion
- In what ways might attempting to balance Corrosion negatively impact our other form?
I don't think this is a huge issue by itself but certain options like recovery moves could easily become too much to handle and end up hurting 30i in return.
- To what degree does the ability to spam Toxic or the poisoned status warp the metagame? Can this be mitigated to the point that introducing Corrosion CAP 30b will still be both healthy for the metagame and effective in fulfilling its concept?
It's a bit hard to say exactly how strong an OU Corrosion mon would be, as there's little to no precedent. That said, there have been many mons capable of reliably spreading Toxic. Pre-nerf Equilibra and Astrolotl used Toxic to punish their scarce checks and even if they would still lose 1v1, it was very easy for any competent team to take advantage of the weakness they created. Zygarde is another notorious mon that abused Toxic to wear down its checks, although in this case it was just one of a myriad of options it had available. Salazzle is the only mon that actually has Corrosion and only saw some niche competitive usage Pre DLC. It was dangerous at times but it was always extremely prediction reliant due to its frailty and in today's metagame it's just completely outclassed. Finally, there's Heatran, which might be the most successful Toxic user of all time. It's presence has always been somewhat controversial and many people have advocated for a ban but nowadays it's mostly agreed to be balanced.
From all these example we can see that an unblockable Toxic is an extremely powerful weapon and it could be argued to be downright uncompetitive but it's not necessarily always broken. That said, while in theory it might be possible to create something balanced like Heatran, I think it's just not feasible to properly balance this with our process, as the difference between completely unviable and horribly broken is razor thin and we're already trying to balance a very volatile ability like Tinted Lens, so trying to add another challenge like this is almost guaranteed to be too much for us.
General thoughts: Picking something as volatile as Corrosion would be risky if this was a normal process but considering that we're also trying to balance a second form too, I think choosing this ability is just guaranteed to come back to bite us very badly one way or the other.
Water Bubble
- What new routes for 30b does having Water as a secondary STAB open up? In what situations would this be the most beneficial? How does this run the risk of being too potent of an ability, and can that risk be reduced in any way?
Well, considering that offensively Poison/Flying is just average, having a supercharged 3rd STAB is obviously going to help, especially given that Water-type coverage would help against many key matchups like Corviknight and Heatran. As for ways to reduce risks, I think being conservative with what moves we give away should help with that a lot.
- What strategies are bolstered by a resistance to Fire typing and an immunity to burn? Can this ability be used in a purely defensive manner while still being “optimized”?
While there aren't that many relevant Fire-types right now, this resistance could let us outright counter Heatran, which would be huge, although honestly I'd much rather use the more targeted Thick Fat if we really wanted to pursue this role. Going physical would be the optimal way to capitalize on the burn immunity although even with a specially biased spread, it would be a decent advantage to avoid the residual damage. As for using this ability defensively, I think that can work but we need to keep in mind that this is an ability that desperately wants to be offensive, as its damage output can quickly get out of control so we'd need to pay close attention to calculations with Choice Band/Specs even if those might not be the sets we want.
General thoughts: Water Bubble could work but I find it really hard to justify over more restrained options like Thick Fat, which can accomplish the part I'd consider most attractive (checking Heatran) without opening the double water power can of worms.
Stamina
- In what ways might Stamina affect our stats stage? How can this be taken advantage of?
I think being able to hit important benchmarks that allow us to tank most relevant physical attackers would be the most important thing to accomplish, with a minor focus on maintaining a decent offensive presence and having a decent Special Defense to take advantage of our Fairy resistance.
- How can this be optimized without defaulting to giving CAP 30b Body Press?
Simply trying to be a wall seems like a workable option, as our typing already has a lot of important resistances, although unfortunately the fact that Urshifu-R's Surging Strikes ignores any Stamina boost is a huge flaw against one of the most common physical attacker. Apart from being a dedicated wall, using set up moves like Sword Dance or Nasty Plot could be a good way to take advantage of the turns bought by Stamina.
General thoughts: I think Stamina is still a very solid option which could lead to a very interesting product, even I'm not completely sure how we should approach it.
No Guard
- Which attacks would synergize best with this ability? Are there any moves that aren’t immediately obvious given our typing that might provide an interesting path to take?
Hurricane is the most obvious choice, as being able to safely spam a powerful Flying STAB move would be huge and of course making moves like Focus Blast reliable would be great. However, I think that where No Guard really shines is on its support options. Being able to use moves like Sing for reliable Sleep or Inferno for spreading burns gives us various interesting options we could use to apply status in ways that no previous users of this ability have even managed to accomplish.
- To what degree should we be worried about granting our opponent full accuracy on their moves?
I think this is practically a non issue, as you're never going to be banking on a miss unless your back is against the wall and you have no other choice and even in that case you were still going to be losing most of the time.
General opinion: Thinking of it as an utility ability, No guard is one of my favourite choices, as it can accomplish many things like making Hurricane reliable, spreading status, and improving coverage, which should be enough to give CAP 30b a good niche on its own.
Gale Wings
- How do we ensure that CAP 30b can reliably be at full health in order for this ability to come into effect
Heavy-Duty Boots should be enough to make Gale Wings consistent and recovery can give you a chance to go back to full HP even if you took some chip damage. Using moves other than Brave Bird should also help, as we'd get a chance to maintain our HP at 100% if we're threatening to KO our foe. That said, even taking all these precautions, it would still be pretty challenging to keep this ability active through the game, as even the weakest of attacks would force us to use recovery if we want to make it live again, which might be too much of a momentum drain most of the time.
- What options are available for us if we choose an offensive route with this mon? What about a defensive route?
There are various different roles we could take. We could be a dedicated pivot, as our typing should give us many opportunities to come in and Gale Wings can force the opponent's hand forcing predictable switches than any pivoting move could easily capitalize. We could also be a dedicated set up sweeper, as it should be pretty challenging for the opponent to find an answer to us if we manage to boost with Gale Wings intact. Another option could be to take a dedicated Revenge Killer/Cleaner route, simply taking advantage of free switch ins early in the game to exert some pressure and once all our checks have been removed just use our priority to pick off the rest of our foes. Finally a more dedicated wall could be possible but I think ultimately suboptimal, as that wouldn't be able to fully take advantage of the ability.
- How can this be explored beyond the roles that were previously fulfilled by Talonflame?
Trying to abuse a priority Roost more could have been an interesting, more defensive route back in Gen 6, but after its nerf, I don't really feel like we could have a different role than Talonflame did back then. The main difference of course would be that we're going to need to be much more careful if we want to use our priority multiple times in a game.
General thoughts: Overall, Gale Wings seems like an powerful but clunky option; it can be hard to activate but when we do the payoff could be worth it. I would prefer a safer option but this is still not a bad route to take.
Thick Fat
- How can improved defensive matchups against two typings be optimized?
CAP 30b would be in a very unique and interesting position if it got Thick Fat, regarding Heatran in particular. We're already immune to Toxic and Earth Power, if we were to also resist Magma Storm and had a decent coverage move, we could actually become one of the best counters against it, something that could easily give it an important niche in the metagame, as any other of its checks can be crippled with Toxic or hates Magma Storm+Taunt. I think that using this ability to neuter a mon that has been notorious for being difficult to check for many generations now would be a fantastic way to optimize this ability. Apart from Heatran, we'd also have a good matchup against Astrolotl, non-Psychic Volcarona, and non-Thunder Punch Blaziken. It should be relatively easy to win these matchups, although Astrolotl should still be able to cripple us with Will-O-Wisp or Thunder Wave.
- Given the attacking power of many popular Ice types in the CAP Metagame, how much of an impact would this ability truly make without completely overloading our stats stage?
While it could be feasible to check Ice-types like Weavile and Kyurem if we had enough defenses, I don't think we should focus too much on the this Ice resistance. We might end up checking one of them if one of our defenses is high enough but trying to target them directly wouldn't be very productive, as we'd need to invest a ton on both defenses to the point were we'd likely have to sacrifice a lot of our offensive presence. That said, not being immediately forced out by these common Ice-types should be an invaluable asset by itself and we'll almost certainly make good use of it so I don't think this really makes our use of Thick Fat any less optimized.
General thoughts: In my opinion Thick Fat is one of the best options available, as it helps against a few key metagame threads and gives CAP 30b a very distinct defensive niche that no other Pokemon can replicate.
Filter
- In what situations is the general defensive boost against super-effective hits most impactful with regards to our typing? Are there any particular interactions with highly viable mons that are noteworthy?
In our situation, Filter feels a bit underwhelming, as even with it most of the time super effective attacks will deal too much damage for us to easily sponge (Just for example: 252 SpA Life Orb Krilowatt Thunderbolt vs. 248 HP / 144 SpD Filter Mandibuzz: 193-228 (45.6 - 53.9%) -- 41% chance to 2HKO). That said, Filter could really shine if we use it alongside Calm Mind/Bulk Up, as with enough base stats, we could make CAP 30b practically unkillable on the side we're boosting. Unfortunately, this would require some very generous defenses to even be feasible and our typing is not really good for a bulky sweeper like this, as we're very easily walled by common threats like Toxapex and Corviknight.
General thoughts: I think Filter would have been a really cool choice for our first ability but with our current typing there are much better options right now.
TL, DR: No Guard and Thick Fat are my favourite options, I also support Stamina and Gale Wings, and I dislike Corrosion, Water Bubble, and Filter.