Purple Zard is a reference to his Gen II shiny sprite. His current shiny colors were first used in the Gen III games.
Rosalina's moveset is really strong... Most characters shouldn't even try to grab her unless Luma's halfway across the stage, projectile users weep if they're laggy enough that they can't bait Gravitational Pull (nevermind the fact that said projectile can hit the original user if they're close enough), and she's got enough range and mobility to play a decent defensive game while waiting on Luma to respawn. That's a lot of strong traits with very few meaningful drawbacks.