397. The talking cat will turn out to be a shapeshifter, usually a really hot girl.
398. The main villain will always be resurrected, and somehow becomes way stronger when he/she/it comes back.
399. Sisters are always attracted to the same man (most often the main character).
400. Anime males do not get erections. Instead, all the blood that would usually go into the penis (to make it erect) goes out of the guy's nose.
401. Or perhaps it is the inverse; since horny males lose so much blood out of their nose, there is no longer enough left to achieve an erection.