Steph Kovacs came, but pretty much only to drink. Sitting alone at the bar while this party's going on is a degree of poor schmuck he isn't yet, but his toga covered him pretty well. He's not interested in letting it all hang out today, sorry!
What dress code? Gamora was the literal fly on the wall, because outside of Rocket and Nebula, she still doesn't know anyone. She partook in some of the food, and for a little bit, managed to be her old sassy self.
Mal came in toga, with a mesh tank underneath for added coverage, but it still showed off his scars and his military tattoo. He can't drink or eat and is still a little shaken up by the visions he had, so he parked his butt on the floor and stared at the sky instead.
Geralt is only there because he wants to know how the Gods party. No toga, sorry.