Tsk, come join in with the wild speculation, or I'll be forced to have my 'Chomp use Earthquake. : )
Hmm...Flying? Bug? Really I have no idea what that thing is, wish they'd hurry up and tell us already. It does seem to be highlighting the ear shape, which makes sense if, say, it uses its ears to fly with, but that could work for either Flying or Bug. Or Dragon (doubt it), or even Normal.
Well, one thing is for sure, they could all be Cuteness types, Espeon and Umbreon are especially adorable with that serious look. ^_^