User blog comment:KaiserLos24/Yasuo's Assailants- Upcoming Champions (Includng Yone)?/@comment-5331854-20131210111444

Resurrected Yone? Unless he's a slave, he won't have a real reason to chase Yasuo anymore (you could say that after the match, Yone believes Yasuo before he fades into the afterlife). Plus, he's buried in a single, improvised grave somewhere besides the read, so it's unlikely that a necromancer/Zaunite will find the grave in some time.

Unnamed warriors? They may be talented, but it's implied they've got killed, too. Plus, they seem to be "normal fighters", not the cremé de la cremé that Valoran can offer. With the exception of Jax (who had a personal recommendation from a formely big name), you need to be unusually good in your field to have a chance to get into the Institute of War, despite them accepting almost every agenda.

Some characters are just that: Characters. We have quite some characters going around in Runeterra that aren't champions.