I appreciate all the answers guys.
The reason why I was asking is that for my current campaign, I plan to have a very powerful balor awaken in Undersigil, unaware of who he is (other than name), how he got there, what he was doing before, nothing. To add to the mystery, despite his awesome power (he's a 52 HD balor), his destructive nature and anger/hatred of (most) things appears to be curbed substantially. The PC's will have to figure out who, or what, did this to him and why (and then decide what to do with him after all is revealed).
While im on the subject, out of curiousity, what order do the powerhouses rank in terms of each other? The Solar is almost assuredly the strongest (I think in 2ed they could summon titans?!) but after that its a coin toss (as far as my knowledge goes). Ideas/Opinions?