If I ride the wind to an uncontested Battlefield where my opponent just entered, my unit is stunned but higher might, what happens?

To use Ride the Wind on a stunned unit moved to an opponent's battlefield:

1. Timing and Sequence

• The Move: When you play Ride the Wind, you choose a friendly unit, move it to the battlefield, and ready it.
• Showdown Transition: Because your opponent has already entered this battlefield, your arrival causes the battlefield to become contested. Because units from two opposing players are now present, the non-combat showdown transitions into a Combat Showdown (Rule 459.2 and FAQ #10229).

2. Combat Resolution

• Stun Status: Rule 423.1.a.2 specifies that stunned units lose the stunned status at the beginning of the next Ending Step. Therefore, if the unit was stunned before the combat, it remains stunned during this combat showdown.
• Combat Damage: Per Rule 423.1.b, a stunned unit does not contribute its Might to damage during the Combat Damage step. Even if the unit is "readied" by the card effect, it does not clear the stunned status, and the unit will not contribute its Might to the combat.

Summary

Playing Ride the Wind moves and readies your unit, but it does not clear the "Stunned" status, which persists until the next Ending Step. Because the unit remains stunned during the resulting Combat Showdown, it will not contribute its Might to damage, regardless of being readied.

Note: I could not fully verify this ruling against the retrieved rules.