If anything, the monster animations generally aren't great. They look very stiff, i mean, they are probably intended to, but it just doesn't fit in GBA anim era i think.
Does Xenoblade Chronicles tell you the age/heights of the main characters? If not, then here:
In order of
Shulk - Reyn - Sharla - Fiora - Fiora - Riki - Dunban - Melia. That would be from top to bottom Shulk obviously being top of the list.