Re: Litten, it might only be black because of its fur being so oily as it says on the official website, and not the typical ‘black=dark’ thing. If they’re going with the bomb/explosion motif, and if the marking on its head really is based on the symbol for brimstone and not just random stripes, we could see something totally weird like Fire/Steel or even Fire/Rock.
Eh, I think they’re likely to stay away from “totally weird” on the starters; they want starters to have broad appeal, rather than be quirky and niche. But sure, rule nothing out. As always, I am the very soul of apathy as far as predicting things about upcoming games.