The Hero's Ally

Possibly the Hero's best friend, closest ally, and one of Hero's largest problems. Might be another member of Hero's race, a Flying Guide, Flying Non-Guide, Small Cute Animal, Small Cute Animal Plus, GREAT BALL OF LIGHT, Animated Inanimate, Robo Buddy, or what have you.

The Hero's Ally As A Side
If they're too small or weak to fight alongside the Hero or provide some other kind of useful service (i.e be a guide), they're more of a side than an ally. As a quick note, the difference between a side and an ally is that sides are usually there Just For Show and attracting a younger audience who like things such as Small Cute Animals while allies actually do something to help their friends.

The Hero's Ally Types
Nutshell: The sidekick-type friend who does their best to help out the Hero and the rest of their team.

Enhanced: The sidekick-type friend who rarely screws up, is loyal to their team, and always lends a hand in battle.

Cruel: The sidekick-type friend who either messes around/up often or eventually betrays their team.

Inverse: The Villain's Henchmen.

Atypical: No mirror.

Wrong: No mirror.