Question

Since Regigigas has a horrible ability then is there a move to eliminate that in a single battle?

Answer 1

No, there isn't a move that can evade the effect of an Ability, Especially on Regigigas and its bad ability. Another example would be the worst ability available:Truant. There is no move that surpasses the ability. Hope this helps...

Comments

Truant is worse than Slow Start. Probably the worst ever!!
But great answer.

Answer 2

Unless the pokemon gets hit by gastro acid, there is no way it can evade the ability.Gastro acid is baton passible.
http://www.smogon.com/dp/moves/gastro_acid

Comments

I specifically said I wanted something that is not just for double battles. Gastro Acid can only be used in double battles by an ally.