It's extremely situational to do this, but I use the move skill swap on it. You'll swap abilities, giving you truant, but once they use entrainment, they'll give you your old ability back, and truant is no more.
later..
It does not work on Pokémon with the Truant, Zen Mode or Multitype abilities. ( so if you just happen to have an Arceus, Darmantian, Slaking, or a truant Durant of your own, you might have a chance!)
lol..