Now that changeteam has been removed, there's no way to manually balance roflstomp matches. I've had a couple matches today where I would of liked to switch teams to help them out/make it a bit more fair, but can't do that anymore.
I think they said that they'll be implementing a manual team switch function in the future. Probably something that won't allow you to create a 2+ player difference in the teams or put a team above 6 players like you could with changeteam