It's CoroCoro leak time. Firstly, a new Alolan variant has been revealed: this time, it's Alolan Grimer, which is now a Poison / Dark type. At the moment, we don't know anything more about it.
The other two reveals do not have their corresponding scans, so right now this information is speculative and completely unconfirmed. While these are probably real, we are missing the usual proof, so take these with a very large pinch of salt.
The unconfirmed leak reveals more evolutions for existing Alolan Pokémon: The first is that Jangmo-o evolves into a Fighting / Dragon Pokémon, whose Japanese name is Jarango, which in turn evolves into Jararango. (Presumably, it Mega Evolves into Mega Jararararararango...)
Surprisingly, Type: Null also evolves into a Pokémon known in Japan as Shiruvadi (シルヴァディ). Shiruvadi also changes type based on the items it holds, due to its new "AR System" ability, much like Arceus does. Indeed, Type: Null and Arceus have a lot in common – perhaps deliberate, as Type: Null was created to be "as strong as the Pokémon of mythology."