Hi,
I recently got two of these fish. They aren't territorial at all, and they are always following each other around. If possible, you should get at least two (mine were the only ones I've ever seen, and the store no longer stocks them).
When I got them, they had ich and were undernourished (all they had to eat was leftovers from the platies in their tank and whatever algae they could find in the bare, algaeless tank). But they recovered and are now plump, active, and ich-free. So I guess my limited experience is that they are fairly hardy.
By the way, they love blanched zucchini slices and commercial veggie rounds, so it shouldn't be too hard to get them eating well.
Just make sure you are getting Parotocinculus jumbo, as I think maybe some other species are occasionally called "pitbull pleco." The links other members gave should help with this.
Hope this helps!