This is stage 3-11, the second to last level in the Mt. Snow region.
After the white team wins the festival in level 3-10, "The Day Of," Cat Clancer appears and tells them that the Professor has been captured by Lunar. Marina demands the cat to reveal the location of the Professor. The cat agrees that, if Marina can win in a dodgeball fight, it will take her to Lunar.
Defeat Cat Clancer at Dodgeball.
Beat the cat clancer without crossing the line and without taking damage.