I thought, "ah, it's the type". I've only caught some common pokemon, but it did seem to be rat = empty ring, spearow = empty ring, wing. paras = two (that might be poison, bug, it was hard to see).
But I think those most likely have a move from each type too, so I can't actually tell which is true yet.
icons flash up at the top of the screen briefly, which I think indicate the type of the Pokémon
But I think those most likely have a move from each type too, so I can't actually tell which is true yet.