I was wondering which would be best for a Smeargle (I saw this but I don't know if it's outdated) for catching purposes.
Doodle Entrainment Role Play Simple Beam Skill Swap Transform Worry Seed Gastro Acid Core enforcer
These are all the moves that can affect abilities. Of these only Simple beam, worry seed, Gastro Acid, entrainment, core enforcer and Skill Swap actually affect the target's ability. In regards to the other question the 3 moves they listed for ability changing are still all good and Worry See/entrainment work just as well as the other moves for changing the target's ability. Core enforcer is not good for removing abilities when it comes to that smeargle set because core enforcer does damage that may kill what your trying to catch.