Dance x Lust
Bad sans poly (Sub Night for extra points)
Dream x Dust
Cross x Killer
Ganz x Color
Kink (Killer x Ink)
Outer x Error
Dream x Horror
Ink x Blue
Error x Sci
Insomnia (Error x Dream)
Dream x Reaper
Blue x Horror
Killer x Horror
Sans x Sans
Limbo (Geno x Nightmare)
Purgatory (Geno x Dream)
Ganz x Abyss
Mecha x Kin
Mecha x Dream
Abyss x Dream (HAHA DRESS)
Killer x Abyss
Geno x Abyss
Cross x Geno
Nightmare x Horror
Another one bites the dust(Reaper x Lust x Dust)
Reaper x Cross
Geno x Outer
Outer x Blue
Outer x Fresh
Ink x Geno
Abyss x Nightmare
Geno x Error
Error x Death
Sci x Outer
Killer x Horror
Fresh x Epic
Dream x Classic
Sci x Dust
Error x Nightmare
Nightmare x Ink
Epic x Cross
Cross x Error
Dream x Ink
Fresh x Dance
Fresh x Lust
Sans x Ganz
Outer x Red
Doublerainbow Ink x Ink
DoubleGlitch Error x Error
DoublePixels DS! Error x Error
DS!Cross x Cross
Killer x Dust
Blue x Outer
Ganz x Nightmare
Ganz x Blue
Lust x Blue
Dust x Epic
Ink x Reaper
Dust x Geno
Error x Abyss

Weird List that I should throw out the window (I got most of these from a rare pair blog on Tumblr)