When a team member falls in battle or when several teammates lose HP, your team should put your heads together and discuss which powers to use to solve the problem.
Sometimes, ideas can clash, and it can be tough to figure out how to proceed. Team captains can be helpful in these situations. They will have the last word on decisions, which lets the whole team take action and move forward more quickly.
The team captain should be someone who thoroughly understands how the game works. It is not mandatory to choose a team captain — alternatively, you could even have two. Whatever suits your team best!