The only good part of Poro King is already in ARAM
As the title suggests, Snowball was already added to the regular game mode. Outside of that, all allowing you to pick champions does is ruin the intent of the map's design. It's not much different from the issue of people making ARAM-only accounts so they can pretend they're good while guaranteeing an advantage in a mode that isn't serious.
Poro King just isn't a good game mode.
every game otherwise they're guaranteed to be on both teams