Pretty much the entire core cast, minus Goh and the rivals unfortunately (tho at least a number of them made cameos in previous eps), watching the battle!
Incognito Rose and Oleana and Todd Snap also spotted!
Twilight and the Pokémon TV show have precisely the same problem: they established a pattern of introducing new characters, then stop after just two. Ash has Brock and Misty, the first two gym leaders, travel around the world with him, but why stop there? Why not keep recruiting every single gym leader he meets until, by season eight or so, there's a town's-worth of world-class expert Pokémon trainers following this random thirteen-year-old, sleeping on the ground and wandering around aimlessly? And why does Bella stop acquiring monster-boyfriends after the second book? Wouldn't Breaking Dawn be so much more fun if it was a vampire, a werewolf, a succubus, and a zombie fighting over her? And it could've kept on going until Forks, Washington was mostly populated with horny monsters obsessed with this one teenager. And, as for The Wizard of Oz...