A Couple/Tag Team Champ(s)

I think it would be very very interesting to have a couple/two friends/siblings be a new release. You play a single champion at a time, but their ult can swap them out (like Jayce's ult to swap to his hammer/gun modes) -- It would possibly make the game slower, but if done correctly, you could have both champions present at all times (with only one usable until swapped with the ult.)

I don't know. Think about it.