you just need to talk with them several times
idk how and ally works
they don't help you in the fight
very grateful to whoever explained to me how they work
When you talk to someone, three options will pop up.
You need to select the correct one. Usually after 5 or 7 correct (character dependant), they'll ask to be your ally.
They don't help out. But they'll give you some stuff each morning and any time they win a lot, you'll get a small cut of the height they gained (and vice versa)