[@Kazemitsu]  How OP are we talking here?  You mentioned the black dragon and his acid breath, but meanwhile Metroid has enemies popping out of lava or acid, existing in subzero temperatures, and so on.  And on top of that, Ridley himself is a flipping SPACE dragon who works with giant lizards, a cyborg brain, and an interdimensional ghost alien.  Whichever character you choose - or a new one if you're up for it - I'll have a look and see if anything doesn't make sense for Metroid.  I mean, that's difficult, but you know...