I think Alcreamie is a 2 stage line (with a pre-evo) or possibly an evolution, which would be weird. That's the thing with new Pokémon, even though we have the leak talking about Pikachu and Meowth, the thought of a new Pokémon getting a Gigantamax form AND an evolution, seems, weird. Like, the Gigantamax form would totally overshadow the evolution.
Also, Corviknight and Drednaw could perfectly have pre-evolutions, but again, if the goal is to find the special Corviknight or Drednaw that can Gigantamax, nobody will focus on getting the pre-evolution that will evolve into a common specimen, so the pre-evolution gets overshadowed. So I feel like they might end up being 1 stage lines, unless Corviknight really is the regional bird.
I still have doubts about Duraludon. It could end up being like Haxorus, but I also feel like it could be the pseudo, despite its design. But I give it 3 stages too.
And Rolycoly, I feel like it's gonna be 3 as well, like Geodude. Yamper will get 1 evolution.