I notice that Varkid evolve when they are injured and then brought amongst other varkid. My theory is that when a varkid is evolving it must be aware that it is vulnerable in that state. Therefore it will only evolve when it thinks it's safe. Only problem is that it won't evolve alone with you watching it unless it's a last resort thing.
I've been playing this little game that I call "Varkid herding" where you simply herd the Varkid from one location to another. Which can be difficult since they will only follow you so much. You'll need also need a low level to constantly provoke them, the low level should purposely die as well to keep the Varkids active.caustic Caverns is the best place to do this IMO. Now you've got me wanting to evolve an Ultimate Badass Varkid. I've been trying with my friends with no luck yet.
Hmm that sounds about right. I noticed that they evolve more when there's a big group. Me and my friend were trying it at the farmhouse in tundra express, since there are lots of spawns there, and you can hide in the barn.