In all my other universe I make unicorns very underpowered, because frankly they are really overpowered. They can do anything and earthpony or pegasus can do but faster and better. It always made me mad but I didn't really care at the same time. But it really made me kinda hate Starlight. She's always seemed like a brat having a tantrum to me. So in this Au I decided to make her an earthpony. I think it makes her decisions and motivations less bratty. I think it really improves her character. She uses her staff for all her magic instead, and uses it for her later battles with Twilight. Also in this AU, she doesn't get re-deemed. She stays evil and her hatred for unicorns grow.

Extra: I'm also going to headcannon all those magic relics that unicorns use to make their magic stronger in the show, were actually made for Earthponies or pegusas.

Also I know someone else came up with earthpony Starlight, but I have no idea who, if you know who, tag them in the comments please