the first time i injected rhythm heaven ds into a wii u virtual console game i was like "well the colours are kind of dark and shitty but i'll live"
then this time i followed a more advanced guide and it turns out that in the internal emulator settings, there's a number for "how dark and shitty do you want the colours to be" and i just set it to 0
@noiob i think it was this one https://gbatemp.net/threads/wii-u-nintendo-ds-virtual-console-inject-guide.480668/