Y'all are thinking too much inside the box. As shown by Maude, Bulk Biceps and other characters, characters aren't really limited by their species. Bulk is not so good at flying, and is a lot stronger than most pegasi. Maude is clearly stronger than even the average Earth Pony, at least in regards to rocks. So really any character can be useless or OP, it just depends on whether that character conforms to the stereotypes attributed to them.
Actually, that's literally one of the points I made; you cannot attribute the abilities of a specific pony to the entire race.
