So I’m going to breed a Bidoof (With a Ditto). It’s a Female with the ability Unaware. Bidoof has two abilities, Simple, and Unaware. Will the chances be 50/50 on the ability being passed down? If not, why? This is in Pokémon XY.
No, breeding a Pokemon with two standard abilities won't give a 50/50 percent chance of either ability in Pokemon XY. According to Serebii,
"If the mother has their ability in slot 1, then the baby has an 80% chance of hatching with that ability, and 20% for the second ability and viceversa if the mother has the ability in the second slot." Source
Before Pokemon Black 2 & White 2, the baby Pokemon had a 50/50 percent chance of inheriting the mothers ability.