Green Goo

This green goo is seen in The Missing Pokemon Movie where TheGamerFromMars searches what it is online. It was given to TheGamerFromMars by the Man in Black in The Disturbing Mystery of Perplex City.

The Disturbing Mystery of Perplex City
In the The Disturbing Mystery of Perplex City after declaring that he won TheGamerFromMars is given the green goo by the Man in Black, who then leaves the room.

The Missing Pokemon Movie
In The Missing Pokemon Movie TheGamerFromMars plays it with it for a while but then realizes something is wrong. We then see him searching what it is online when he stumbles across an article stating that alien slime was discovered beneath the Earth's surface.