Necrosia is a demonic/humanoid looking pokemon, having seven eyes and possibly two mouths. It appears to be based partly on a jester and a pendulum scythe.
If using one, it has no weakness unless if it reappears in Procyon and Deneb, where Fairy types exist. While it has no weakness, it does not excel that well in offense due to having two types that are walled by Dark types unless if it runs Brick Break. Still, 99 Speed and 120 Attack and a strong defensive typing along with Levitate make it a strong Mon that is immune to 4 out of 17 types in the game.
Not to be confused with the Gen VII Pokemon Necrozma.