Eijiro, an animator on Sega’s upcoming game Bayonetta, was able to talk about enemy animation and how he approaches this complex task.
Enemy animation is unique in that it acts as a cue for how the player should react. And when it comes to attack animations, the process is split into two parts: the precursor, and the actual attack. Eijiro explains that the way an animator approaches these two sections directly affects the difficulty level of the game, as an enemy can easily come off as too predictable, or not predictable enough.
Eijiro included the following videos to showcase these two parts to every enemy attack:
[Source]