Number Six: because “champion” pretty much means “the SINGLE best”. There can be only one.
There is an idea. Let them settle it the old fashioned way. Give all the players swords and let them have at it (only clean beheadings count).
You’ve got me there. “Champion”, being singular, definitely does indicate only one.
“Champions”, on the other hand, is plural, and indicates more than one, as in “Teams A and B are co-national champions.” Use the proper inflectional ending, and there can be more than one.