SNES
The Picture Processing Unit (PPU) used in the Super Nintendo Entertainment System has a 15-bit RGB (32,768 color) palette, with up to 256 simultaneous colors.
However, while the hardware palette can only contain 256 entries, in most display modes the graphics are arranged into between 2 and 4 layers, and these layers can be combined using additive or subtractive colour blending. Because these blended colours are calculated by the hardware itself, and do not have to be represented by any of the existing palette entries, the actual number of visible colours onscreen at any one time can be much higher.
The exact number depends on the number of layers, and the combination of colours used by these layers, as well as what blending mode and graphical effects are in use. In theory it can show the entire 32,768 colours, but in practice this is rarely the case.
Read more about this topic: List Of Video Game Console Palettes, Nintendo