When I /tp a mob to another entity, its body rotates correctly, but its head does not. According to MC-97963, the solution is to set NoAI = 1. But even with NoAI set, the head still does not rotate. In fact, this issue occurs even with Giants, who have no AI, and even Giants with NoAI = 1 have the problem. There seems to be no way at all to rotate a mob's head. Which means that if you're teleporting them along waypoints, they look very odd facing a completely different direction than their body.

To reproduce:

In a repeating command block chain, put this:

/tp @e[type=ArmorStand,c=1] ~ ~ ~ ~1 ~
/execute @p ~ ~ ~ /teleport @e[type=ArmorStand,c=1] ~ ~ ~10
/tp @e[type=Giant] @e[type=ArmorStand,c=1]

The /teleport is just because the mob won't rotate at all if the /tp would keep it in the same (x,y,z) coordinates; this way, you can walk around to keep the armor stand moving and the body rotation active. Then summon a NoAI giant and place an armor stand down.

/summon Giant ~ ~ ~

You'll see despite having no AI whatsoever, the head won't rotate properly with the body; this is true of all mobs, but since the giant has no AI to begin with, it highlights the problem best.