Without looking at stats, what kind of odds do I need to call a 3bet (when I opened)?

What about effective stacks 100BB, I open for 3x, villain1 3bets to 9x and villain2 calls, and I'm holding small to mid PP, do I have odds to call?

What kind of stats do the villain need for me to make this kind of call?

I only tend to set mine in 3b pots with >130bb effective stacks and also if the 3better is tight, or if I opened in early position and they 3bet. I 4b bluff or fold if I'm opening BTN and they 3b from blinds if they're looser.

anyone else?

It's ok to setmine in the situation you described, the 3-bet is pretty small and you have an extra caller too and you're closing the action. Though, if both players are decent then probably not.

I wouldn't setmine in HU pots at all, or when the 3-bet is bigger (unless deep).

depends on alot of things really, not just your stack, thier stack and bet sizes etc, you also need to be pretty sure they are stacking off when you do hit a set and you probably also need to be prepared to barrell good boards for you that dont flop a set. Its a bit like asking how long is a piece of string. its more going to be down to the opposition you face and your ability to play profitably post flop, but if you are asking this question i would say try not to call 3 bets with small pps unless its multi way.