Thank you for the extremely quick and thorough response, @estcst!
You are right - Mike mentioned something along the lines of finding it preferable to earn his money the hard way rather than having an easy ride, so there is no doubt that he must have demanded/Moody must have offered him some cash for his services. Unless it was a symbolic amount (which is probably unlikely), it would be hard to argue that Mike was motivated by altruism. However, it is possible that he took a liking to Moody and his friends, which may have played a part in his decision to intervene on their behalf.
It's in a sense interesting that once the tide starts turning against Mike (during his second fight with Linderman), Moody overcomes his fear of Ricky and tries to give Mike a helping hand. I personally found it slightly out of character for the leader of the bullies - Moody didn't appear to be particularly brave in his previous encounters with the 6 foot 4 Ricky, but in this instance he didn't want to leave Mike hanging. Maybe Mike and Moody didn't have a purely businesslike relationship.
It's debatable whether Mike would have agreed to torment Clifford, Carson, and the other smaller kids. I personally got the feeling that he would have been reluctant to do that, as he would have found it difficult to justify it to himself and it wouldn't have done his "tough guy" reputation any good. Mike's fighting skills aren't too shabby and I have to admit that he showed bite to his bark during the final scene.
I sure wouldn't want to fight Mike. He's a solid guy. Maybe not a great fighter but good enough. I think Moody jumped in as a way to protect his interests. Carson says after Linderman took off that it was worse than before so I take it as Moody was up to his old tricks.
As a side note, Hank Salas (who played Mike) use to stop around IMDb and/or YouTube from time to time to talk about My Bodyguard. I haven't seen anything from him in a long time but it seems that he had a really good time working on the film. So if you see something that seems like it was posted by him it may well have really been him.
If I didn't know both of them, I would have probably found Ricky as intimidating as Mike (especially when he has a very sullen look on his face). Mike had the muscles, as he was probably into bodybuilding, though he was likely not a very experienced fighter and Ricky held the height and weight advantage. I agree - Carson seemed to imply that Moody, Hightower, Dubrow, and Koontz had upped the ante in the absence of someone like Ricky to keep them in check.
Very cool, I didn't know that! It's always refreshing to read the insights of the actors themselves, as they are able to dispel many of the myths surrounding the films. It's good to hear that Salas enjoyed himself on-set.