Mario’s Head Can Move In Any Animation!
Standing Still While Moving Head
At this point, you may already know that using the Freeze button will freeze everything related to the camera. That means, position and angle.
While the camera is frozen, it will not move when you use the C buttons, not even when entering C-UP mode.
So, to make Mario’s head move while the camera is frozen, just Freeze the camera, and enter C-UP mode. Mario will move the head just like he does normally, but this time, the camera angle will not change.
Any Animation, Really!
You can also move the head in any animation! But only while standing still. This trick is achieved by replacing the animation called Reading sign/First person pose in M64MM. This is the animation that plays when the C-UP mode is enabled, so if you replace it, the animation you replaced that one with will play here.
Try it out yourself and find which animations you can use for different situations!