Super Mario Galaxy 2/Grandmaster Galaxy

Star 1: The Ultimate Test
This galaxy is unlocked by getting 120 Power Stars and 120 Green Stars.

Star 2: The Perfect Run
Repeats star 1 only under daredevil conditions, some enemies are replaced by tougher ones and Rosalina is on an extra planet. It is unlocked by giving 9999 star bits to Banktoad and completing the first star.