At least Iris was a main character in the anime for an entire arc, although she wasn't a Champion there. (And, a lot of fans hated her, ie. "You're such a kid!" )
The sad thing about Lance is that he's not only neglected, but also gets routinely bashed by the fandom. :( Fans like to twist him into being some evil hypocrite who cheats and hacks his Pokémon, completely ignoring his acts of kindness and heroism. Or worse, they equate him with his wildly OOC Adventures counterpart and paint him has some angsty, murderous villain.
Meanwhile, these same fans hold up a blank, personality-free player avatar as the Greatest Trainer Who Ever Lived. :rolleyes2:
(And, last I checked, this girl kicked his butt at Mt. Silver. Who's the strongest trainer now? At least she doesn't resemble a certain eternal 10 year old twerp with a non-evolving yellow rat.)