Usually it's helpful to add a little more context than that
I assume you mean with Giratina in Malamar. Most decks don't really care too much about Giratina, all it's doing is either setting up counters to make Sky Scorching Light work, or adding the last counter or two when the numbers don't quite work. As an offensive piece, it's a fairly decent offensive Pokémon, but nothing amazing.
The simplest way to deal with it use
Girafrig, which will eliminate the threat. If you're not *that* worried about it, then I wouldn't bother with it, just kill it when it's in active and otherwise target other things, and try to keep Sky Scorching Light from doing its thing -Acerola, Max Potion, etc., or just ignoring it will be fine.
But it really depends on what deck you're playing. Lost March has a lot bigger issue with it than Zoroark.