Whenever you bring up the screen where you can power up / evolve your pokémon, the currently selected pokémon is shown against a background up top (excuse me for not bringing any images for this). If you pay close attention, you'll notice that the background actually changes depending on what type the pokémon is. For example:
- Bug types get spider webs,
- Fire types get flames / embers,
- Psychic types get a, um, psychedelic background?
- Rock types get a mountainous background,
- Electric types get electric zaps running along,
Now, I have caught many pokémon, hence seen the backgrounds of most types, in particular all of them except flying, dark and steel. There are no dark types among the original 151, the Magnemite line get the electric background, and the only pure flying type in the entire series (Tornadus of gen V) won't be introduced in the game for quite a while. Every flying type currently in the game is dual-typed and gets the backgrounds of its other (non-flying) type, so I have yet to see any flying type background.
Do the flying / dark / steel backgrounds exist in the game, waiting until the likes of Umbreon, Tornadus and Registeel are released? The fairy type background exists and is visible for e.g. Clefairy, so arguments based on generational issues seem unlikely to properly answer this question. Are there also any (presumably hacked / mined / extracted) images of these backgrounds to have a look at?