Swampert's is a bit over-dramatic; much like it was in Colosseum and XD. (since the fainting animation is still the same) I think its probably the longest I've seen on PBR, at the moment.
Skarmory's is pretty interesting; staggering for a little bit, before flashing out its wings, then falling to the ground. Sort of like a Phoenix raising from the ashes.. only in reverse... heheh...
I'll agree with Shen, as well; I think its pretty funny that in at least the games from Colosseum to present, Kadabra knocking itself out with its own spoon is pretty hilarious.
Weavile looks like it wants to deal one more blow to its opponent, before it faints, then collapses in a heap. Poor thing...
Definitely Honchkrow, as well. Its pretty funny, as well, how it takes hits. XD
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As for ones I don't like... one of them is definitely Probopass. It has some sort of... seizure, throws its "heads" off, then just... hits the floor. I seriously rose an eyebrow at it.
Not because I dislike the animations, but I dislike any Eeveelution (including Eevee) fainting; especially when its my own. (like when it gets "stolen" in Neon Colosseum) My Poor Jolteon got nabbed, in a battle I had there, recently... ;.; Vaporeon's and Espeon's look especially painful to the poor little Eeveelutions... ;-;