The earthbound series has some WEIRD enemies, but it also has, what I believe, the strongest enemy in RPG history. Subject A, the Ultimate Chimera, from Mother 3. When Lucas is investigating the Chimera Labs to find Salsa the monkey, 2 of the Chimera's escape. The 1st is the Almost-Mecha Lion. It is tough, but just a regular boss. But when you get back, the pigmasks working there are speaking of "The Big Red One". One of them warns you, "If you spot it, Just Run." That is the Ultimate Chimera. Mother 3 has a mechanic where if you run into a weak enough enemy, you will instantly defeat it, even without a battle. If the Ultimate Chimera spots you, it will run into you, and if it touches you, it bites down, and you get a game-over. It's only weakness is a button on it's back, and fortunately for Lucas, Salsa the monkey presses the button, delaying it just long enough for Lucas and Co. to escape.