What does Getto Daze mean?

It really does depend on the context, though. "Getto da ze!" can mean "I'll get one!" "I got one" or "I did get one." It's really one of those things that changes depending on the situation.

In addition, "Pokemon Getto da ze!" is sort of the tagline for Pocket Monsters the way "Pokemon - Gotta Catch 'Em All!" is the tagline for Pokemon.