Now get the other Giga Cards. At the
Big Wave, you can buy one, and you can buy another from Deep
Space 2. The last one is in a locked mystery wave. Go to where
you fought DragonSky EX, then just hold down until you are on the
invisible path. Go down and get the card.

[edit] Woah, fuck the what? I'm glad Owlsey has his own account now...