The RV page of the Paragonwiki summarizes it pretty well.
The AVs themselves aren't too bad but depending on your situation you might need at least 4-6 other people helping you because you usually have to fight 2 or 3 of them at the same time. I'm sure there are people who've managed to solo them but my guess is that most people can't manage that.
The only real challenge about it is that you're in the middle of a PvP zone so you're easy targets for anyone who wants to poke at you. If you're lucky you'll get them done before you draw too much attention. The bad side of that is that each time the AVs spawn they'll spawn randomly so if you're unlucky you may have to try multiple times to get the AVs you need.
Good luck. 
Loth 50 Fire/Rad Controller [1392 Badges] [300 non-AE Souvenirs]
Ryver 50 Ele� Blaster [1392 Badges]
Silandra 50 Peacebringer [1138 Badges] [No Redside Badges]
--{=====> Virtue ♀
Regarding spawning them, you want the section on the linked page, "Zone Event", which says:
Quote:
| When either side controls their fourth pillbox, reinforcements spawn to support the other faction in the form of two to three Signature Heroes/Villains. At the fifth pillbox another wave of support is spawned if the first set of Signature Heroes/Villains has already been defeated. |
Paragon City Search And Rescue
The Mentor Project
Hey forum, I want to get the villain AV defeat badges in RV, but I have never gone after them before. I was just wondering how to get them to spawn?