I tried a version of this deck out last night. Admittedly my trainer line was pretty different, but my diagnosis ... this combo is too slow for the current format. I tested against Blissey/Arcanine, Mario, Infernape, and Empleon. The only win Golduck/Xatu got was against Mario and a lot of that had to do with Xatu hitting weakness and being resistat. It was really hard to get Psyduck built & powered AND get a Xatu on the bench to get things rolling. The few times I got it going things were fun ... but it was just too hard to get setup and keep it setup against good decks.
Natu is an interesting starter. Can be hugely disruptive.
Xatu is a good card and makes for a very good secondary attacker.
Psyduck is flippy but OK.
Golduck isn't as good as I had hoped. Both attacks are interesting but I'm just not feeling the love.