Number of games are best guesses if I don't recall, and I'm not motivated enough to find out.
Atari 2600 - 6 or 8 Sega Master System - (I can only think of 6) Sega Genesis - 30'ish Sega Saturn - 15 or 20 Nintendo 64 - 1, K.I. Gold PlayStation - 10 or 15? Dreamcast - 5?
Genesis... There'd be days I'd skip lunch at school just so I could save up to buy a Genesis game.