I like Mawile’s design a lot but it also equally confuses me… I’m assuming the feminine side with the yellow… fur? Is that where her head is… or is the brain in the plant-trap looking thing? And why Steel Type when it looks plant-like? Anyway, my point is to ask what do you think about her history/biology? (is it biology when its a Steel Type?)

I actually really like Mawile as well.  She’s one of the Pokémon I lump with Farfetch’d, Dunsparce and the like, where they’ve taken a really clever design, made it awful at everything, and then forgotten about it.  Poor Mawile…

Anyway.  I am led to understand that Mawile is probably based on an obscure Japanese monster – a woman with a second mouth growing out of the back of her head.  Game Freak seem to have adapted the idea by combining it with the concept of an animal which uses markings or unusual appendages to appear larger or more threatening than it really is (unlike, say, Girafarig, Mawile doesn’t actually have two mouths; according to the Pokédex the extra ‘jaws’ are really horns).  It’s a very fun, creative design, and I think it’s a shame Mawile had to… y’know… suck so much.  In answer to your question, then, just ignore the big jaws – that’s what she wants you to focus on.

As for why they decided to make her a Steel-type… you know, I honestly have no idea.  Her origins seem to fit with her being a Dark-type, and she’s portrayed consistently as a deceiver.  The Pokédex very insistently describes her jaws/horns as being made of steel, but that seems like it was a later choice to justify the typing, not the reason for it.  Quite aside from that, she has few typical Steel-type powers.  I guess you could interpret it as Mawile deliberately cultivating the appearance of one type when she actually belongs to another, thus continuing the theme of deception and making it more difficult for her enemies to attack her.