I think that Ax probably had the MOST problems.
He's marooned on a planet that supplies all his physical needs, once he gets acclimated (recall in the Andalite Chronicles that Loren responded badly to the Andalite atmosphere, which means that their lungs require a different chemical composition in the air than Human lungs).
His only social contact is with people not of his species.
He's been thrown right into the front lines of a MAJOR war, and he's just a kid.
He's expected to know more than he really knows.
He's viewed occasionally with major distrust.
He may never get home, as far as he knows.
This guy has ISSUES, folks. You would, too, in his position.