LKN-351 is absolutely right, free and premium members can be promoted, even to Kingpin etc., and do everything.
Nasiri (Overlord) in the above is on the free account, he can invite, promote, demote, make coalitions and so on. So yeah, free and premium players can hold whatever rank they like. He's completed Tier 2 of paragon rewards. (he's a very shifty individual, am not sure you'd want him in a paragonwiki lounge, or watch your wallets!).
So: no limitations for free and premium accounts as members of Super Group?