There were actually a surprising number of them ported to Gameboy Color, who’d thunk it? I was so excited about the Wonderswan port, I got the console just for only playing With You ~ Mitsumete Itai, but man the sound is bad, Neo Geo Pocket Color is way better than Wonderswan, who’s the genius who screwed this up? Neo Geo Pocket Color still the best option for Bishoujo games on the go:
Infinity Cure
Memories Off Pure
Pocket Love IF
Super Real Mahjong Premium Collection (Portable boobies on the go babee!)
Wonderswan Color has:
Debut
Graduation
Kiss Yori
Memories Off Festa (Not even, more like a card game.)
With You ~ Mitsumete itai
Gameboy Color has:
Pia Carrot e Youkoso! 2.2
Sakura Wars GB
Sakura Wars GB2
Love Hina Pocket
Love Hina Party (Half mini games, half dating sim supposedly)
Gameboy Advance has:
Love Hina Gorgeous
Sister Princess
Supplement this list with your finds.