Lets say I have a benched Ralts. In that particular turn, I evolve it into Kirlia. Am I allowed to use Evolution Wish to evolve the Kirlia into a Gardevoir?
Anyway, if an effect tells you to do something, you do it, even if that action would normally be illegal. So you can use Evolution Wish on a Pokemon you evolved normally that turn.
What you couldn't do is use, say, Wally's Training to search your deck for Kirlia and evolve it, and then play Gardevoir from your hand to evolve again. Wally says it "counts as evolving that Pokemon". That means playing it and evolving with it is considered as if you'd played the evolution from your hand -- so it counts as your one per turn for that Pokemon. Therefore, you can't play another card from your hand and evolve it a second time that turn.
So it works one way, but not the other. You can evolve and then play something that breaks the rules, but you can't break the rules and then evolve normally.