Dragon Ball Z: Budokai Tenkaichi 2 Cheats

Grandpa Gohan
First, In the what if story "Destined Rivals" Go to the story when you are Goku, then fly over to Kami's Look out on the map. Instead of the Look out, you should arrive at King Kia's world. Talk to him, then he should say he has a surprise for you. You will start a fight at the Martial Arts Tournament, Then you should start fighting Grandpa Gohan. If you win you should unlock:
Kid Goku
Master Roshi's Pupil.

Then go to the Majin Buu Saga pick Story 11. When you get to the map, go to the roadside. There you should see Yamcha, talk to him and defeat (Not Survive) him. You should get a Purple Potara called Fox Mask.

Go to Z item fusion and fuse Master Roshi's Pupil and Fox mask. Then you should get Grandpa Gohan!