I actually researched the situation and it's more complex than it seems, but ultimately Nintendo's VC for GB and GBC doesn't seem to support SGB modes.I'm interested about this as well, how does the official Pokémon Yellow VC on the eShop do it?
Pokemon Yellow came out late in GB's lifespan when GBC already existed, in case of Pokemon Yellow it had the color palettes information built into the rom itself.
But Red and Blue (and Green in case of Japan) didn't have have the palettes in the rom, as such they turn up black and white no matter what.
Here is where SGB (Super Game Boy) comes in, which was an addon for SNES that basically was GBC hardware with some extra enhancements and pre-programmed color palettes for certain games locked in a big SNES cartridge with an adapter for GB and GBC cartridges.
SGB's pre-programmed color palettes apparently included support for some games that didn't have color palette information, such as Metroid 2 and... Pokemon Red/Blue and Japanese Green and Yellow (Yellow in Japan came out before GBC and didn't have built-in color palette information).
Many GB/GBC/GBA emulators actually do emulate the SGB mode which includes the pre-programmed palettes which is why you can get Pokemon Red (and thus also its romhack Pokemon Brown) in color on those emulators.
The VC emulator doesn't support it unless there's some hidden function we don't know about that would require hex editing the code.bin
Bottomline is, if you want them in color you will need to find an emulator that supports SGB mode.
I found out that GameYob does have SGB support, though the 3DS version of that emulator has less than stellar audio compared to its DS counterpart, so if you have a DS flashcart I recommend using the DS version of GameYob just for the better sound.
I'm going to test RetroArch's GB/GBC emulator now and let you know how that works.
Edit:
RetroArch's Gambatte doesn't support SGB, so the only option right now is GameYob.
Last edited by Canzah,