Not sure about the does-this-make-Dry-Skin-the-worse-ability-ness, but I wanna suggest Turboblaze. I can imagine sending out CAP3 and reading "CAP3 is radiating a blazing aura!" Of course there are some abilities that Turboblaze negates that would have to be considered. A few that jump to mind are:
Flash Fire
Levitate
Magic Bounce
Sap Sipper
Water-immunity abilities
Electric-immunity abilities
Status-immunity moves
Flash Fire because it's the mostly used ability of Heatran, a Pokemon that seems like a good counter for CAP3. With FF, Heatran is immune to both of CAP3's STABS, and it can hit back with Earth Power. Even with Turboblaze active CAP3 might not take a chance against Heatran, but it's just a consideration . . .
Next is Levitate. I don't know if CAP3's gonna get and ground moves (unless I completely missed movepool discussion or something?) and I'm not sure if Turboblaze is gonna scare off the Levitate users, but I just thought I'd bring it up.
Now for Magic Bounce. Basically means that CAP3 can lay the nasty on Espeon with moves like Toxic and Will-O-Wisp, and whatever other status moves it may get. I could allow CAP3 to burn/poison Espeon on the switch but otherwise I think CAP3 would be running from a predicted Psychic . . .
Then I'll just lump together the rest as "immunity moves". The absence of Sap Sipper could allow CAP3 to Solar Beam something (Azumarill?), but I don't see this being the difference between life and death. Electric immunity abilities could be taken into consideration, but this depends on CAP3 getting any electric moves (aside from HP Electric). Same goes for water-immunity moves, although these are mostly held by water types who could scare off CAP3 with water moves. Plus, the only water move I imagine CAP3 with would be Scald. Could be uses to burn Jellicent, but I think Jellicent hates Toxic the most. Plus, CAP3 will most likely have Will-O-Wisp to burn it.
As for status immunity moves, the two which deal with the status CAP3 will most likely have access to are very thinly spread: Immunity is given to Zangooze and Snorlax, the former which has Toxic Boost and the latter which I can't find an analysis for that uses Immunity. Now the other status-immunity moves: Insomnia (or variants), Limber, and Magma Armour. Let's just rule out Magma Armour right now unless someone sees CAP3 with a freezing move. Turboblaze could allow CAP3 to put to sleep pokemon with a sleep immunity, or paralyze a pokemon with Limber. All depends on what kind of moves CAP3 gets access to, I guess.
Well, that's about all I have to say for now . . .