For a member of Team Baka, Assist Wriggle is surprisingly good, at least for me. Here's my build.
Name: Vanessa
Mark: Green
HP: S Rank 0 EVs
FoAtk: S Rank 64 EVs
FoDef: S Rank 64 EVs
SpAtk: S Rank 0 EVs
SpDef: S Rank 0 EVs
Speed: S Rank 2 EVs
Ability: Bad Medicine
Skill 1: Camouflage (Status, Raises accuracy by two stages. Pretty much the only reason I wiped post-game Sakuya with Wriggle alone)
Skill 2: Power Drain (Focus, Recovers half the damage you deal. Just watch out for Bad Medicine)
Skill 3: Natural Beauty (Focus, Change to lower Focus Attack, and is slightly stronger than Power Drain. I use it when I have no need to heal right away.)
Skill 4: Heavy Poison Gas (Spread, Chance to heavily poison the enemy, but unfortunately does nothing on Steel types)
Item: None (I'll give her one eventually)
Has anyone else been able to make a powerful Assist Wriggle? I'd like to see your builds.