Hobgoblin leads the Six! Why? Because he's an unrepentant, manipulating ****bag. Also, if we must EVER have Hobgoblin, as a leader and manipulator of other villains would be the way to go, since it would prevent the audience from getting bored with Goblin action.
The backstory would be that a good portion of the villains had already been introduced, and he someone manipulates/threatens/bribes/"does whatever he has to do" to get the other five guys to more or less work for him; playing on their emotional/mental/financial weaknesses.
The word "team" would apply only very loosely, if at all. They're all in it for their own reasons; I don't want any "supervillain team meetings." There is one guy in charge, one guy pulling the strings, and there is no trust or mutual understanding among the group. I mean, they're bad guys. Naturally, to a certain degree, the group would have to cave from within.