Ray most likely wont defeat or maybe even fight Garling in gv.
Garling is hailed as the champion of gv. And is now basically the no 2 of the wg and the right hand man of imu. He is clearly being set up as an end game villain for someone like Dragon. And he was in the final 12 panel too.
He's clearly way more important to the end game. So i doubt oda would downplay him by letting him be defeated by anyone in GV.
Moreover, Ray's retarded captain was fighting AGAINST Rocks and TO PROTECT the CDs in GV. So Ray fighting Garling doesn't fit in with his retarded captain's actions.
Ray will probably rescue Shakky from some fodder, and maybe fight one of the top Rocks pirates like Shiki.
Do no bet against the Father of the Author's Fav