Shadow Guy

Shadow Guy and Gamma Gal as they appear in Card Jitsu.

Shadow Guy is a superhero that works with Gamma Gal. They normally appear in the Stage play, "Squidzoid vs Shadow Guy and Gamma Gal". They also appear in a Card-Jitsu card.

Costume

Shadow Guy wears a blue and gray costume with a Blue Cape, a Blue Superhero Mask, and a belt that says SG (his initials). His costume helps him blend into the shadows.

Can shoot glowing blue plasma from his hands.
Can combine his shadow waves with Gamma Gal's plasma beams to create yellow lightning bolts.
Can transform into a shadow and move around.

He appears in Card Jitsu as a special attack along with Gamma Gal.
If you put on the Shadow Guy Costume and do the wave action, you will do the Shadow Wave (which looks like a blue energy ball).
In the Treasure Book, you can still obtain Shadow Guy and Gamma Gal's costume if you have a 'Unlock Items Online code' Code.
He appeared on a one month Membership card along with Gamma Gal.
He is one of the plastic penguin figurines and is sold along with a yellow reporter penguin.
He also appears as a plush toy.
He appears with Gamma Gal in the real book Shadow Guy and Gamma Gal Heros Unite.