>Red and Blue
are opposite in color wheel
>Gold and SIlver
often go in the same sentence but Pokemon Crystal should have been called Pokemon Platinum
>Ruby and Sapphire
gems with colors which have a opposite relationship
>Diamond and Pearl
One is a gemstone, one is made by molluscs. Platinum is a metal. They're all expensive I guess?
Black and White
Inverse
>X and Y
go together as chromosomes, in math
>Sun and Moon
Inverse, opposites
>Sword and Shield
Ok, I get it, they go together
>Scarlet and Violet -- What the fuck??? These two colors have NO relation!!! !