"Alright" as in, he didn't embarrass himself. From what we saw, the fight wasn't short and Ash not only traded blows with Brooke's snake form, he did it unarmed and without any powers. I'd say that's impressive for a human, especially one who's still in training.
Ash is cocky, but considering who he spars with, I'd say he's earned it.
Besides, Chloe isn't Brooke, nor does she have Brooke's natural talent for fighting. We saw that much when she tried to fight Tandy and Gabrielle.Chloe simply lashed out in blind rage, whereas the AA duo used coordinated attacks and had her dead to rights in no time. Lance didn't seem to have much trouble with her either.
That's a stark contrast to both of Ash's showings, since he defeated the entire Ninja Club single-handedly. I doubt an out of control succubus could be any worse than what he's already dealt with.