The Co-Star Luma is an orange Luma that is the playable character for Player 2 in Super Mario Galaxy 2. The Co-Star Luma can grab enemies which freezes them, and can also spin to stun enemies while holding them. The Co-Star Luma can also grab coins, Star Bits, 1-Up Mushrooms, and air bubbles (when underwater), and can bring them to Mario. The Co-Star Luma can activate switches, make enemies do an action when grabbing them, and spinning characters and Lumas. If Co-Star Luma isn't playing in the game to help Mario, he will be on Starship Mario.
Player 2 can make the Co-Star Luma make different sounds by pressing buttons on the Wii Remote.