- Metroid [NES / GBA (NES Classics) / Wii (Virtual Console) / 3DS (Virtual Console) / WiiU (Virtual Console)] - Ridley involved.
- Metroid Zero Mission [GBA - remake, NES original] - Ridley involved (plus a Metal/Robot Ridley).
- Metroid Prime [Gamecube / Wii (Trilogy)] - Ridley involved.
- Metroid Prime Pinball [DS] - Ridley involved.
- Metroid Prime Hunters [DS] - No Ridley.
- Metroid Prime 2 Echoes [Gamecube / Wii (Trilogy)] - No Ridley.
- Metroid Prime 3 Corruption [Wii (single and part of Trilogy) - Ridley involved x2.
- Metroid II [Game Boy / 3DS (Virtual Console)] - No Ridley.
- Super Metroid [SNES / Wii (Virtual Console) / WiiU (Virtual Console)] - Ridley involved.
- Metroid: Other M [Wii] - Ridley involved x3 (Infant, adolescent, ugly duck face adult).
- Metroid Fusion [GBA / 3DS (Ambassadors) / WiiU (Virtual Console) - Ridley involved (well his body controlled by an X-parasite anyway).
So 5 Home Console games and 3 Handheld games that involve Ridley. I didn't include the Trilogy set since it's just a compilation of the 3 main Prime games.
So
8 out of 11 games have Ridley.
Let's throw in Smash Bros. while we're at it:
Super Smash Bros. [N64 / Wii (Virtual Console)] - Ridley involved (Background of a stage).
Super Smash Bros. Melee [Gamecube] - Ridley involved x 3 (Background of a stage, opening sequence, trophy).
Super Smash Bros. Melee [Wii] - Ridley involved x 8 [2 Bosses (Ridley, Meta Ridley), 2 Trophies (Ridley, Meta Ridley), 2 themes (Ridley, Meta Ridley), 2 stickers.
Super Smash Bros. for WiiU/3DS [WiiU / 3DS] - Ridley involved [???].
Then there's:
- Ridley's featured on boxart for 3 games: Metroid Zero Mission, Super Metroid, Metroid Prime 3 Corruption (Japanese).
- Ridley featuring as a cameo in Dead or Alive Dimensions Metroid Stage.
- Ridley featured as part of the Villains promotion for the US eshop (With Bowser and Ganondorf).
- Ridley featured as one of the places on the Nintendo themed Monopoly (Meta Ridley).
- Ridley appears twice in Nintendo Land as 2 bosses (Ridley and Ice Ridley), and have the Ridley theme.
- Ridley appears in NES Remix 2 for the Metroid remix.
- Ridley appears in Captain N and the official (canon) Metroid manga.
- Ridley appears in the live action advertisement for Metroid: Other M.
And the haters say he "isn't important" for the series or isn't as important as the one-shot Hunters, Mother Brain or Dark Samus.
Ha ha, good one.