Oh dear... The riddle is slightly confusing, but I suppose... The person who comes after White and Black's duo attack is... Unless the "character" is two characters, or the name of the attack itself... Is it the Queen?
I'm sure someone who watched the full thing would know on point, but I hardly remember the snippets I watched a long time ago. So, if it's misleading... What about Peace Thunder girl? She can also be split into two, and she's shiny.
Looking back at it now that I have the answer, everything makes sense except for the queen part, but even that guided me to the right answer somehow. Ahem, my turn: Such fun and games, and everlasting feats. They'll cry and laugh -- Oh look, a clown!