What happens if you hack to put Genesect, Keldeo, and Meloetta in to your game?

Question

Will it freeze on me or delete my saved data...?

Answer 1

You would suddenly have them :D
Yet hacking itself is dangerous. That´s all. It may screw up your game

Answer 2

Putting those three pokemon in your game will result in them being in your pokedex. Of course hack at your own risk