Can you use Ride the Wind on an ally's unit?

To determine if you can use Ride the Wind on an ally's unit, we must look at the game's definition of "friendly."

According to Rule 740.1, "Two Game Objects are friendly if they share a controller, or if one’s controller is teammates with the other’s."

Since Ride the Wind specifically targets a "friendly unit" and you are teammates with your ally, their units count as friendly to you. Therefore, yes, you can use Ride the Wind to move and ready a unit controlled by your teammate.

Keep in mind that this is subject to standard multiplayer restrictions—for example, you cannot use this to move their units if you are in a 1v1 game, as you would not have a teammate. Additionally, ensure the battlefield you are moving the unit to is a valid destination based on the game's movement and combat rules.