If villain has very high fold to 3bet and low 4bet, the fix is not to 3bet/fold QQ, but to simply flat QQ pre, but 3bet some air.

2NL. He gets crushed every time he tries 4NL.

Your question is too general. I need so much more information to give you any kind of response. I will answer with, it depends. I'm not folding KK though unless villain is like a 5/1 nit or something crazy.

If a mega nit 3bets then I flat KK to set mine at least; if he's not that nitty then my hand has value. One or the other. You can't be too loose to setmine against but too tight to see showdown with KK against as well.

Against a mega-nit, I will call with any 2 cards if the odds aren't bad. Recently, one of these nits raised to $15 from UTG, got a bunch of callers. I 3-bet to $80 from the bb with 93 off, he 4-bet to $150. I'm not that deep, but I'm also not good enough to fold for $70, so I flat. His hand is face up as AA or KK. Maybe QQ like 10% of the time. Flop comes Q83. Check Check (he is scared of QQ which is why he checked). Turn 9. I bet $150. He calls. River 7 (no flush hits). I shove for $420ish. He tank calls with KK and was very shocked to discover that I had 2 pair (he only considered being behind QQ or AA in that spot).

His hand may be face up, but you know that 93o has about 12% equity against AA, don't you?
Flatting a nit's 4-bet with any two cards is suicidal.

Well, it's certainly not suicide, because I know what he has, so it's very easy to get away from any hand I have including top pair, or even trips if he hits a set.

Anyways, in this hand, I needed to call $70 when there was already over $300 in the pot. The direct odds are only slightly bad, meaning I'm getting the right price to call with my implied odds. If he bets flop, I'm folding here every time unless he mis-sizes his bet again.

i'm probably only mucking KK 150bb+ deep vs REAL nits. you can't get like couple hundred hands and decide whose a nit... you can get a general idea but you don't know.

But if you find he's a real nit I'm probably only folding 150bb+ vs his EP/MP opens

Vs CO, BTN, SB, or BB 3b/opens I'm getting KK in 150deep almost everytime unless he's running less than 15/10 and 3bets like 3% fold to 3b 97% and 4b 3% or somethin lol

you would have to be pretty deep to even bother considering this, you dont have immediate odds and sure you have implied odds but you also have reverse implied odds, if the flop comes K93 or A93 are you still stacking off?also your not going to flop two-pair often enough for this to be profitable long term ever 100bb deep your just spewing money when he shoves on you pre and spewing money when you call a 4bet.