Ok, I just beat Crasher Wake and I don't know where to go next. I know Fantina is the next Gym Leader, but I heard something about having to defeat a Galactic Grunt, or something like that (in a warehouse in Veilstone). I think I need a special key, but I'm not sure. Can anyone help me here? ^^;

There is a Galactic grunt by the Pastoria Marsh, talk to him, and he will flee, you will also face your rival, but after that, keep chasing the grunt till he battles you.

XD
I loved that. It was just too fun making him run.