Excited to see discussion of Wandering Spirit.
So Trace doesnt sound valid for slating at all, so I'll write about Wandering Spirit. I went through the VR and listed all the interactions with mons, the ones not listed dont interact in a meaningful way or likely arent ranked on the VR:
If we go through the VR and just list interactions with mons, a lot of the abilities begin to look similar.
For example:
Thick Fat only interacts with Heatran, Weavile, Kyurem, Astro, Blace, Victini and Volc in the top ranks. Even if we can touch Heatran, Victini's other STAB screws us. I guess Glowking and Zapdos use Fire as coverage, but they both beat us too. Further down there's Syclant, Blaziken, Torkoal and Moltres.
Corrosion: Only interacts with Heatran, Glowking, Scizor, Pex, Melmetal, Skarm in the top ranks. Lower in the rankings there's a bunch of less-often-seen Steels such as Aegislash, Bisharp, Equilibra, Ferro, Kart, Drill. Cawm does not care.
Filter: Weavile, the slows, Zera, Koko, Kyurem, Slowking, Lele, Zapdos. Further down there's Zolt, Zone, Victini and Ttar. You still take a butt-ton of damage from all of these.
Water Bubble: Since people are hyping up the defensive utility, these are the mons we avoid burn from: Pult, Heatran, Pex, Slowking. These are the mons we take reduced damage from: Heatran, Astro, Victini, Volc, Glowking, Zapdos. We lose to Victini, Glowking and Zapdos.
Abilities with constant effects such as Stamina, Cotton Down, Fur Coat/Ice Scales, and the Water-boosting effect of Water Bubble are impossible to analyze in this way because they're always in effect.
From Pip's post, there are 9 mons that
Wandering Spirit can take advantage of. I would argue a few of the pokemon in the "mistaken for being annoyed category" can be taken advantage of in non-niche scenarios. Excluding those, there are still Buzzwole, Cawm, Excadrill and Barraskewda that Wandering Spirit can reliably interact with, plus situationally Zeraora, Corv, Bisharp, Equilibra, Blaziken, Tangrowth. Even ignoring all of these guys as well, 9 is a pretty comparable number to the above abilities. It may not help against any current S rank mons, but there are plenty of relevant, solid mons that it does help against. Teams are not solely made up of S rank mons, and forcing the opponent to play more carefully can work in your favor even if the Wandering Spirit mon never actually comes out in battle.
I am not in any way claiming that Wandering Spirit is stronger than (or even as strong as) the abilities listed above, but I don't think it should be discounted on this basis. I will admit it would probably work better on a mon that isn't dependent on HDB, given the ubiquity of Knock Off.
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Corrosion and
Water Bubble: I think both of these would need a full dedicated process and I would not be thrilled if they were slated, but (if the TL deems them legal for this process) I think they should be slated given the amount of discussion they have generated.
Trace: Should not be slated because Jumbao.
Thick Fat: I like this as an ability, but knowing M-Venusaur saw significant play and probably used it better than 30b can (being weak to both Fire and Ice and having access to Earthquake) makes me uncomfortable. Would prefer this to not be slated, but it was talked about a lot.
No Guard: Would rather it not be slated because M-Pidgeot and Machamp did it justice already. We would probably be building around whatever powerful coverage/sleep move we decide to give it. Not super interesting in general.
Fur Coat/Ice Scales: Don't like them, but don't see why they shouldn't be slated. Pretty boring.
Fluffy: I view this completely separately from the above pair. Far more situational and interesting, with a specific downside. Would be interesting to balance because we don't blanket check every attacker from one side. I like it. Slate it.
Sticky Hold:
oh and sticky hold is boring as piss i dont think its even worth slating cus it stands no chance of winning and it only helps make the two forms more similar which is awful
Stamina: Great ability with interesting paths to explore. No question about legality for this process, and overall positive opinions from everyone who has addressed it. Should be the first ability on the slate.
Filter: Personally don't think we have much to gain from this, but don't see why it shouldn't be slated.
Gale Wings: I would really really really hate not being able to switch in on U-turns. I am very much do not liking this ability. It's legal and generated a bunch of discussion though, so should probably be slated.
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Not to derail the conversation, but I'm going to make one last quick mention of
Cotton Down. It got a bunch of early support, then no discussion afterwards. I still think it's a decent ability, especially given the number of resists we have, especially 4x. It's a balanced ability; it's very good against fast/frail mons and offense, but quite passive outside of forcing switches. In general, I think it's an ability that definitely fits the concept, has great synergy with our typing, and will be useful against any team with any offensive presence.