No, you said that the animations returned even though they made a comeback in Emerald. It's true that Crystal animations had more frames than sprites in other games, but 2 frames is enough for the sprites to be classified as animated.
you should note that they said 2 SPRITES, not frames.
I don't know if you just can't understand this or something, but the two sprites are here:

sprite 1: view of pokemon from behind (lucario is using this sprite)
sprite 2: view of pokemon from in front (lucario's opponent is using this sprite)
each pokemon has 2 sprites, front and back. these sprites are never used together in a sequence to form an animation.