There is an item that can change a Pokémon's Ability called the Ability Capsule, although only between the Abilities the Pokémon can have, excluding Hidden Abilities. So for example if I had a Compound Eyes Scatterbug, if I used the Ability Capsule I could change its Ability to Shield Dust, but cannot change it to its HA Friend Guard.
The Ability Capsule cannot be used on a Pokémon with only one standard Ability, such as Charmander which only has Blaze along with its HA.
Beware that it can only be used once.
So far there is only one way to get an Ability Capsule, and it is to purchase it from the left attendant of the Battle Maison for 200 BP.