Bunny

Max is in fact really into taking care of animals and he feels really interested on them. Euli is not exactly his friend, but she's the only pony that can be with so many animals and actually animals like him. That's one of the reasons Max doesn't pick on her like he does with the other fillies. Of course Euli feels really unconfortable having him around all the time while he's on Ponyville, but Fluttershy always tries to make her get new (some) friends.