No you will never see it again But you do have a very very low chance you find a Pokemon with identicle ivs natures ect But as I said its a very low chance of finding a identicle pokemon Edit: like tiger jay said (she reminded me ) if you release starters legends or fully evolved Pokemon that can not be found in the game obviously you won't be able to find them
No, because if you release a charzard you wont be see it in the wild because as you know you can't get starter Pokemon in the wild (unless you use A-R)