Minimum for group!

I understand groups can’t be 1 person, and the max is 5 people. Can groups be of size 2? Can they be of size 3? Can they be of size 4?

3-5 people is the best!

The reason for a minimum number of 3 is that in teams of 2, if someone bails, the other one has a hard time. A minimum of 3 makes this much more robust.