Star Plati-I mean, Buzzwole GX, seems just a bit too meh for my tastes, especially when Raichu GX can do all of it better.
Nihilego GX is going to be Alolan Muk GX's best friend, which gives me even more reason to run a dark deck in return. It has good HP for a Basic GX Pokemon, Lock up will force the opponent to look for Guzma, and its GX attack will pull off quite the shenanigans-to which I believe is a good counter to Guzzlord GX's Gluttony GX. Speaking of...
Guzzlord GX is what I would call the mid-game sweeper that should be late-game. It has high HP for a basic GX Pokemon at 210 (good Arceus, for a Basic!?), 180 DMG attack with no consequence (3 Darkness and 1 DCE for 180....just, wtf), and a GX attack that, other than if Nihilego will pull off its GX attack first, could win games earlier than usual. Think about it-winning games by using a GX attack when your opponent has three-fours Prize cards left? That's absurd! Of course, the downside is that ungodly 5 Darkness requirement, but even then that could be mitigated by Yveltal's Oblivion Wing and other Darkness acceleration cards. Definitely something to look out for.