>>49844446Red never became a Champion, he only entered the Hall of Fame, being the Pokemon League Champion isn't a title, it's a profession, hence why Steven and Alder have their Trainer Class change to PKMN Trainer after they resign despite being Champions and why Champions that still reside in the League will still have their Champion Trainer Class after you've already beaten them.
As for why Blue, N and Trace weren't called Champions, it was literally a few minutes after they beat the Champion and gen 5 revealed that the League as a whole has to agree on a certain trainer to be the Champion, N didn't battle Alder to be the Champion, he did it to prove he was the strongest and that no one could stop Team Plasma. Blue, N and Trace didn't even enter the Hall of Fame before they were dethroned by Red, Hilbert and Chase.
Lance is the Champion because Red didn't want to sit in a room and wait for challengers to make it past Karen, his strongest team is better than Blue's and Silver's and he actually wants to be the Champion.
