Most of us think of it as the butt-headed duck-thing that breathes fire. However, what if those aren't lobes of skin/bone, but decorative feathers? deviantART's sio-- gives an example of this:
What would Magmar's diet be? It lives in the mountains, near volcanoes in particular. It's most likely an herbivore, perhaps also an insectivore, as it doesn't appear to have teeth (or large ones).
It has a flame tail like the Charmander line (who also happens to live in the mountains), strange large spines on its back (one seemingly protruding from the "collar"), and unlike ducks, it has arms with claws. What are the black rings around its neck and ankles? Are they skin? Feathers? Cooled lava?
It would be terribly hard on the brain of one's body temperature were 2,200ºF, so that's probably a lie....