> Water

You tell him you like to swim, so... water, you suppose.

One final checkmark and Professor Oak puts away the clipboard. "Very well, then. You better wake up soon, you have to go see Professor Rowan bright and early! Today begins the first step of your very own Pokemon journey!"

And with that, he's gone. In the distance you hear something that sounds like a clock alarm. You can either wake up now or do whatever you want. It -is- your dream, after all.