Team up is one of the most welcome feature of the game; it brought me back after the game was becoming tedious in Azteca. But that said, it still needs work. It's no fun being a level 8 wizard fighting Prince Alicaine to have three maxed out wizards come out and end the battle in a single shot, and I'm sitting there with a big 0 XP for the round.
So, here's what I propose. Even if it takes longer to find a team, what do you think about a checkbox that lets the Wizard asking for help specify the maximum level wizard allowed to respond to the Team Up request.