All three of these were done on my Nintendo 3DS in a fun application called Colors3D. These images are actually 3D, and obviously here, they're 2D. To see these in 3D, you'll need a 3DS and then use the internet browser and go to the Colors! website. I'm KelKojiro there.
You can watch my drawing process here: Jessie: [link] Meowth: [link] James: [link]
Sorry for the late reply. I'm not sure if you'll be able to get this printed as a poster since it's quite low res. But feel free to try have it printed anyway. ^_^