You know Red and Steven, right? They're both listed as champions despite clearly not being them anymore.
If I recall correctly, Steven was still said to be a champion a few times in Emerald. If not, he defiantly was in HGSS. Red too, in GSC/HGSS.
They both apparently just passed on their champion role to another rather then being beaten and their role taken from them. Is that why? If you retire you still have your name as the champion when you aren't.
That makes sense.