When you're playing as Gotenks you have to be Super Saiyan to use Super Ghost Kamikaze Attack and Galactic Donuts. So here's the cheat: turn to Super Saiyan 3 and then remove the disc and put it immediately back in. You should then be able to use both of those moves and they should be powered up. You do this the same way with Mystic Gohan except you turn into Elder Kai Unlock Ability then you should be able to use Super Kamehameha instead of having to be in Super Saiyan. This will power it up in the same way.