Well, I dont remember seeing something like this in all my years playing the game and let me tell you that this is completely broken
On the side of good, we got Ethan's Ho-Oh ex, Cynthia's Garchomp ex, Steven's Metagross ex, and Marnie's Grimmsnarl ex, and to oppose them, we got Team Rocket's Mewtwo ex, Team Rocket's Moltres ex, Team Rocket's Crobat ex, Team Rocket's Nidoking ex, and Team Rocket's Persian ex
If your opponent controls a monster that was Special Summoned from the Extra Deck, and you do not, you can also use up to 6 monsters in your Deck as Fusion Materials
It becomes a Raichu
Bounce it back to their hand with a Consider
I have no problem playing 4 of this creature in my deck as they even stack well if you want to Mutate one on top of another for a double card draw