Twice in the last couple of days on threads I have leapt to defend Hoodoo Cornelius's honor after people have commented that he is not a very effective companion. I thought I would start a thread specifically on the little guy, since he is rapidly becoming one of my favorite companions and not just because he is a cute little crazy monkey (although that doesn't hurt).
I love guy! But I admit there was a learning curve involved since his optimal use is very different than other companions.
Normally with companions who have a single special attack/critical hit ability, I use that ability early in the fight. I started that way with Cornelius. But what happened is that he would run up to two or three of the baddies and biff them repeatedly, taking a bit of damage every time; when he was done usually the two or three baddies were half dead or a bit more, but all on their feet. Since Hoodoo Cornelius was (a) my most wounded guy at that point and (b) had a high threat level because of his mighty biffing, pretty much everyone would concentrate all their attacks on him, and down he would go. Everyone else would have an easy time of it finishing off the baddies 'cause HC had already done much of the heavy lifting.
The above is not the way to use the Mighty Mojo Monkey! Don't use his Go Bananas! attack as your opening move - use it as your finishing move. Since I learned this lesson I usually launch the GB! attack about halfway through the attack. He finishes off some of the wounded baddies and, if any are left, they usually don't survive enough to put him down.