The Ultimate Chimera is a mutated Chimera found in the Game Boy Advance video game Mother 3. It can be found in the Chimera Labs of chapter 7, though attempting to battle it is useless and ultimately foolish, as there is no way to kill it. Plus, if he touches one of your characters, then they'll automatically die. A button is placed on the beast's back which, when pressed, will somehow turn it off. Though again, this is useless, as the yellow bird stationed on its head will just press it again to turn it on. So, the only thing you're allowed to do is simply run away from it. It'll appear again in the next chapter, though like before it's invincible.
In Super Smash Bros. Brawl
The Ultimate Chimera is a minor character in the Wii video game Super Smash Bros. Brawl, where it'll appear on the New Pork City stage. It'll appear at random times, and will, as in the GBA game, instantly kill you or your opponent if touched, and will also be indestructible.
The Ultimate Chimera is a pink monster with a long, demon-like tail. He has a massive jaw and a companion bird that loyally sits atop his head at all times, just incase someone manages to press the button on its back, in which the bird will press it again. It's unarguably an odd looking creature, true to the Mother/Earthbound series of video games.