I actually have one from the Jungle Tours in Japan from a long time ago. This one is a legit copy. I have a way of checking to make sure they're real: Check the OT, the ID No., and if they have the correct ribbons. Checking on Serebii or Bulbapedia is always a good idea and should be suggested.Unfortunately they are hacked, yes.
The games prevent legit mythical Pokémon like Celebi from being wondertraded around.
There are ways of circumventing this, but, yes, it involves manipulating the Pokémon, resulting in hacks.
You can keep them if you want.
Just make sure that you don't trade them in this community here.
But, since you're already here, maybe you can trade for a legit Celebi here in the future?![]()