i have three gold wolffish in with about 5 bichirs, a peacock eel and two hujetas. i've yet to see any aggression from the wolves towards any of my other fish but they often snap at each other. my biggest is about 8" the next is around 6.5" and the smallest is about 5.5". The biggest sometimes chase the two smaller ones, the mid sized one chases the smaller one occassionally and the small chase no one (besides feeders). I don't know if I'll keep the wolves together because i don't want any of them to die but sometimes I'll walk in and they will all be swimming in a big circle together at the top like everything is fine. But to answer your question, they seem to get along fine with the bichirs, eel and gars, its just each other that they sometimes have a problem with.
i have a rainbow wolf as well and the bichirs that are in the tank with him lie all over him all the time. the rainbow and my lazy retropinnis bichir share the same "resting" spot. their is a knife in there with him too and he doesn't bother any of them. everyone in there is in between 6-8".