[He doesn't bother to answer Krillin's first question, because he feels like that's a no-brainer as well- but the second question, that's a good one and so he turns to the center console and beckons Krillin over to view it.]

Multiple things. Simulations just like the one I put you into, making you fight with no sort of power whatsoever. You can program it to do almost anything you desire, whether it be creating weapons, enemies, or even scenes from home. I've used the tournament grounds a few times to fight against others. It made for an interesting battle. The only downside is the gravity can only go up to ten times that of Earth's, so I don't even bother.

Be as creative as you like, whatever gets the job done. Some of the functions can be confusing, but, anyone with half a brain should be able to figure it out well enough.