I know in real life people can't fight for 45 minutes without getting exhausted, but I don't really think it's as much of an issue for characters that operate on the Dragonball scale.

Really, the whole team thing makes little sense anyway. Goku and Geets are universe busters, so anyone who can realistically challenge them is just going to curb stomp anyone else anyway. The team might get some entertaining fights, but they won't really be relevant to the outcome (barring some sort of joke character like Roshi winning the entire tourney, which could totally happen.)