Depends on the individual pokemon. They seem to be somewhat capable of taking sides, so there COULD be an Evil pokemon as we know it. Of course, in its opinion, it isn't evil, but everything else is. No one would identify themselves as evil, for they would see their opponents as evil.
Technically, any pokemon that is a predator to another pokemon is evil to the prey. Any pokemon who hurts another pokemon could be seen as evil to the injured pokemon. It all depends on context.
There is no more evil pokemon then there is evil people. In the right state of mind, what can be seen as evil, could actually be good to them.
I have no clue if this rant is coherent, due to sleeping troubles, and exhaustion, so yeah. This is, I think, what I mean to say.