Hello!
I am not an admin just a regular member.
For over three years since I become a member and longplayer, I think the recommended longplays resolutions needs to be updated because new consoles has been introduced like: Nintendo Switch, PS VR, PC-FX, etc.

Here's the list for recommended resolutions but Nintendo Switch, PS VR, etc. needs to added:

Microsoft >> Xbox: 720x480 (480p), 1280x720 (720p)
Microsoft >> Xbox 360: 1280x720 (720p), 1920x1080 (1080p)
Microsoft >> Xbox One: ??
Sega >> Master System: 256x192 (rescaling to 512x384 required)
Sega >> Mega Drive / Genesis: 320x224 (rescaling to 640x448 required)
Sega >> Dreamcast: 640x480
Sega >> Mega-CD: 320x224 (rescaling to 640x448 required), 256x224 (rescaling to 512x448 required)
Sega >> Saturn: (TODO)
Sega >> Game Gear: 160x146 (rescaling to 320x292 required)
Nintendo >> NES: 256x224 (rescaling to 512x448 required)
Nintendo >> SNES: 256x224 (rescaling to 512x448 required), 512x448
Nintendo >> DS: 256x384 (rescaling to 512x768 required)
Nintendo >> Wii: 720x480 (480p if possible - not supported by all games)
Nintendo >> Wii U: ??
Nintendo >> GameCube: 640x448, 640x480
Nintendo >> N64: 256x224 (rescaling to 512x448 required), 640x480
Nintendo >> Game Boy Color: 160x144 (rescaling to 320x288 required)
Nintendo >> Game Boy: 160x144 (rescaling to 320x288 required)
Nintendo >> Game Boy Advance: 240x160 (rescaling to 480x320 required)
Nintendo >> Switch: ??
Nintendo >> 3DS: ??
Sony >> Ps1: 320x240 (rescaling to 640x480 required), 640x480
Sony >> Ps2: 480i (avoid), 480p, 576p, 720p, 1080i
Sony >> Ps3: 1280x720 (720p), 1920x1080 (1080p)
Sony >> PSP: 480x272 (rescaling to 960x544 optional), 320x240 (rescaling to 640x480 required)
Sony >> PS VR: ??
Sony >> PS4: ??
Sony >> PS Vita: ??
Other >> FM-Towns: 352x232 (rescaling to 704x464 required), 640x480
Other >> PC Engine / TurboGrafx 16 / CD: 256x232 (rescaling to 512x464 required), 320x256 (rescaling to 640x512 required)
Other >> PC-FX: ??

This is just my opinion after all.

you missed xbox one ps4 nintendo wii u 3ds ps vita

Thanks for remind me Spazbo4. The list has been updated.

I think for PS1 need to add more resolutions which supported by this console:
- 320x256 for PAL region (rescaling to 640x512);
- 512x240 (rescaling to 512x480);
- 512x256 for PAL region (rescaling to 512x512).

They already are. Although in some cases a second aspect corrected version can be included as well (640x512) even if only for ytube if it looks much better. The original untouched aspect upto 2x version must still be retained for archive.

Longplays of PAL games with 512px height will be forced to 480p by YouTube anyway, because 512p isn't standard resolution for YT.

Intellivision: 352x208 (resized with Nearest Neighbor via VirtualDub, not cropped), 318x192 (cropped and resized with Nearest Neighbor via VirtualDub), rescaling to 636x384 required for submissions.

MSX1: 256x192 (cropped), rescaling to 512x384 required.

MSX2: 256x212 (cropped), rescaling to 512x424 required.

Nintendo >> Wii: 480p (if possible - not supported by all games)
And also for the european longplayers: 576p (only for PAL games they doesn't support 480p - only possible on Wii U)
Nintendo >> Wii U: 1280x720, 1920x1080 depending on which native Resolution the Game has (Here a List of some games and their native Resolution)