Smudge

Using brush tool to create a round sphere.

Image source:

Pikachu (link) 

Using lasso tool to crop out pikachu and combined it with the grey ball.

The shadow needs more perfection. Anyone wants to help? :O

Opacity

Using different opacity to create an image.

I also flatten image at the end and use smudge tool.

Image sources:

Background Smoke: (link)

Palm: (link)

Fire: (link)