Rotating game modes should have all champions available

{quoted}

because some have game breaking bugs that cant be fixed in the time span that the mode is out and others are cancer to play against like urf ryze

I think OP was mostly saying "Not just the ones you own" Though obviously some champs are bonkers in certain modes.

Though I think in One for all, it's more that any champion owned by at least one team member, Otherwise, the champion pool would be restrictive if it only allowed you to vote on champions everyone owned. But that's more or less an Necessity, While Riot would rather encourage you to buy the champions you wanted to play. (even in RGMQ)