Most psychology PhDs don't receive gun training in school, tranquilizer or otherwise. Not sure about cursed zombie entrapment (that could be covered during mandatory intern hours), but Dr. Samuel James Loomis is somehow capable of all these things. At one point (Halloween 4), he agilely escapes death by diving behind some convenient barrels while his un-killable former patient takes out a gas tank with a truck, causing a near-fatal explosion.
Dr. Loomis' constant attempts at shooting Michael Myers really only impede the guy's momentum. It only takes the first two films for Loomis to realize that bullets just don?t work. At the end of II, he decides to be the martyr and blow both Michael and himself up using a combo of oxygen and ether.
Oh wait... but they both survive... somehow. Maybe Loomis got the explosive recipe wrong. But that's great because then we get him for four more films! In those films we get to see him use Michael's female prey as bait to lure him into a trap consisting of a metal net, a tranquilizer gun, and his fists. But it's when he uses his shrink skills to reason with the monster that we think, "Oh yeah, hey, that's what he was trained to do." And Michael almost listens... until the Doc tries to take his knife. Don't do that. He likes his knife.