Shady Move - Pokémon Rulings Compendium

What are the rules for using Banette GX's "Shady Move" Ability?: You can move 1 damage counter from any Pokemon in play to another Pokemon in play; it can be different player's Pokemon or it can be the same player's Pokemon (either you or your opponent).

Source: Celestial Storm FAQ (2018-07-20), TPCi Rules Team (2018-08-02)

If there is more than one Banette GX in play can the player perform "Shady Move" more than once (i.e. perform Shady Move with active, then retreat, switch, etc., perform it again with the new active)?: Yes, you could do that. However, going to the bench does not allow the same Banette GX to do Shady Move again; you are limited to one Shady Move per Banette GX per turn, assuming you can get them into the active slot.

Source: Celestial Storm FAQ (2018-07-20), TPCi Rules Team (2018-08-02)

What happens if I try to use Chandelure's "Shady Move" Ability to move a damage counter from my Pokemon to one of my opponent's Pokemon while they have a Machoke with "Daunting Pose" Ability in play? And what happens if I try to move one of my opponent's damage counters from one Pokemon to one of their Benched Pokemon.: In both cases Shady Move would remove the damage counter from the first Pokemon, but the second Pokemon would not receive it because it is protected by Daunting Pose. If you try to move damage *to* something that blocks effects, the damage disappears; if you try to move damage *from* something that blocks effects, the damage stays there. But Daunting Pose only prevents putting damage counters ON your Benched Pokemon; it does not prevent taking damage counters OFF your Pokemon.

Source: Guardians Rising FAQ (2017-04-22), TPCi Rules Team (2017-05-04)

For Chandelure's "Shady Move" Ability, am I allowed to move a damage counter from one of my Pokemon to one of my opponent's Pokemon?: Yes, you can.

Source: Guardians Rising FAQ (2017-04-22), TPCi Rules Team (2017-05-04)