Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
I've got a bug on prankster moves magic bounced to dark users and failing (saying that they are immune). I've just tested on 3ds and the magic bounce works fine (as usual) on dark prankster users too. As you can see. http://replay.pokemonshowdown.com/gen7ou-530112286
I've got this bug on Golisopod's ability, emergency exit, where it hit the HP below 50% by an attack and the ability did not activated. It happened with me more than once already. You can see in this battle:
http://replay.pokemonshowdown.com/gen7pokebankou-492956739