3rd Gym I think I got by fine with an Pikachu outspeeding and Paralysing it before it can Hypnotise me, and killing with Thwackey afterwards. Or if you have a Carkoal, it resists all of Stantler's attacks.
4th Gym, the easiest way to deal with Drifblim is a Strong Jaw Boltund with Crunch and an Awakening.