Deus ex machina is more someone/something intervenes to quickly wrap up the conflict. I always say Deus ex machina timing for the rapid-than-normal ending. Anticlimatic is the proper term here. But, that's a good observation on your end. I don't think I'd say it's Deus ex machina, as more the series off/on power/type gauge.
Like how Ash's Grass Pokemon always beat the Rockets' Poison types, for example? Or in this case, Tauros vs. Metagross? I say that because it was disconcerting seeing the Alakazam who kicked so much booty in the previous episode be able to be beaten so easily here. After that, it went downhill for me.
And, yes, it's clear Anabel is an empath or some form of a telepath, yet the series won't outright play on that and state it. Of course, if they do that, they'd have to acknowledge Anabel's clear inspiration: Sabrina. The previous episode made that paricularly clear as they swapped out Sabrina's tragedy with Anabel's androgyny to make the new psychic distinctive. Ironic as they've recycled a theme before and openly affirmed it, while here, not so much.
That's the only theory I could have for her not being able to detect her opponent's Pokemon -- the writers and the fact being the final battle was 1/3th of the episode instead of normal. The previous episode had at least a little more time to work with. This was begging for another episode, just to get Anabel's quirks and further exploration of her empathy. I enjoyed the first act as the gang tried to attempt her empathy and Ash actually attempt to train, but both acts come off as belonging in two separate episodes instead of being mishmashed here.
And this is the second Frontier Brain to have feelings for someone in a twist ending way. What's next? Brandon is going to fall for May? Heh. Please.
Still, Anabel was intriguing for being a male-ish girl instead of the usual girly men and her dub voice was rather appropriate. I know she won't return, but think of the issues you can use with her. So many ideas....