What are the characteristics of a perfect team mate? What are the characteristics of a monster team mate?

Answer 1

A team mate could be in a sport, or common activity like group project, etc.
In my view, a good team mate would understand his assigned role in the team, do his best to fulfill the role, cooperate with other team members in their roles where he has to interact with them, have the capacity to mix and get along well with the other members, and be helpful to others without offending them, so as to achieve the group's objective.
He should of course be well-informed or knowledgeable in the area of his position in the team, and should put forth his views gently and persuasively so that others are clear about his contribution.
Team work is a difficult job, and one needs to keep ones personal prejudices and attitudes under control when working with others towards a common objectives.
I suppose this is an ideal view of a perfect team mate!
On the other hand, those who make it very difficult to the team in its work, obstructs the group's activity, behaves badly or does not contribute his talents fully to the team and its members, would be a difficult team mate.

Answer 2

A perfect team mate, plays the game by the rules, shows up for practice and gives 100% to the game. Monster team mate is just the opposite.