YouTuber Pannenkeok2012 has made one of the more interesting videos i've seen in quite some time that covers everything there is to know about character's blinking in Mario 64. Apparently not all character's in Mario 64 blink but the ones that do are somewhat diverse. For instance Goomba's have two eye states with eyes open and closed yet Mario has 3 eye states of eyes open, eyes partially closed and eyes fully closed.

You can also check out more Pannenkeok2012 videos that focus on other interesting things related to Mario 64 like in game pause buffering and what happens when you talk to Yoshi with negative lives.