Does skill swap synchronize ability work for SOS battles?

Question

I have done a bunch of research and I cant find an answer to this situation I have.

Im shiny hunting a beldum and I want adamant nature on it.

But its impossible to shiny hunt without a ghost type and no ghost type gets the synchronize ability.

So my idea was to start with Synchronize gardevoir with adamant and skill swap the beldum, let gardevoir faint.

So now I have a fainted Pokemon with the desired nature in slot 1 of my party.

Then just use a shedinja to get it to 1hp with false swipe, and switch to trevenant.

Now with trevenant use skill swap and obtain Synchronize and give harvest to beldum and trick the leppa berry.

So now will Synchronize on TREVENANT work and change the nature of the beldums that I knockout to the adamant nature of my fainted gardevoir in my first party slot??

I dont wanna start a chain find a shiny just for this to not work.

I tried a few times but haven't got any luck and that could be the 50% and me getting unlucky but I wanted to ask to verify

Answer 1

In SOS Battles, if a Pokémon with Synchronize is in the first slot of the party when the wild Pokémon calls an ally, there is a 50% chance that the called ally will be forced to have the same Nature as the Pokémon that was originally in the first slot when the battle began (which is not necessarily the Pokémon with Synchronize)

Source

I'll admit, I had no idea you could do this.

Based on the information you have given, I believe you are doing it correctly. Adamant Gardevoir opens the battle, Skill Swap, and faints, (you can even use Healing Wish to faint instantly). Trevenant comes in and Skill Swaps back to receive Synchronize. All further allies called should be 50% Adamant.

Be wary it's only 50%! That's a huge chance for the undesired outcome to happen.

As far as I can tell, you are doing this correctly. If someone else notices something that disagrees, let me know.