The October edition of the Japanese manga magazine CoroCoro has leaked. First images show a Poison/Dark-type Grimer while upcoming scans are supposed to show the evolution of Jangmo-o, a Dragon/Fighting-type.
In the first scan, Grimer has now received two teeth.
According to Serebii.net, the evolution of Type: Null is also shown in the magazine. The Japanese name of the new Pokemon is allegedly Shiruvadi, which changes types depending on the item it holds.
However, this is all speculation at this point until further scans and translations become available. But the leak has Redditors already talking, especially about Shiruvadi and a possible Arceus connection.
This is a developing story. Check back for updates.