SNES

Emulators
Use Snes9x or higan.

Screenshots
Use Snes9x for screenshots, since higan currently does not support screenshots. Do not use ZSNES for screenshots, since it does not render the bottom line of the screen correctly.

In Snes9x, press F12 to take a screenshot.

The screenshots should be saved as PNG or GIF.

The screenshots' resolution should be 256x224 or (rarely) 512x448.