Never. Regardless of whether I send it out at the beginning of the fight or in the middle, I have never once seen Feliger fall asleep upon being sent out.
Unrelated, Serra's Frosmoth seems to have something funky going on with its speed? It outran my Zoroark (162), which should not be possible without a choice scarf, but was slower than my Cinccino (184). It should have 125 speed at this level with maximum investment. Am I missing something here? Does Laser Focus give priority, maybe...?
EDIT: I saw someone mention earlier that Fern's Mega Arbok didn't petrify properly. This also happened to me.