and if not ports in the technical sense, good game boy “versions” of games more famous on other systems.
off the top of my head, there’s
contra - actually my favourite contra game tbh. just a really nice distilled version of the concept. there’s a colour version that was only released on an official multicart in europe!
nemesis ii - pretty decent shooting game with some great-looking graphics and storytelling
avenging force - probably one of the more famous examples of this phenomenon, it just really works. and for some bizarre reason, the only consumer version of this game for decades.
super mario bros. - also contains smb2j/lost levels as an unlockable extra. playing this was my first exposure to smb1! (but not marion in general, obviously)
donkey kong country - not actually very good in retrospect, but it has an exclusive fishing minigame, so it’s noteworthy at least
mortal kombat - i think this was the first version of the game in which goro was a playable character
mortal kombat 3 - you could enter kombat kodes as a solo player at your leisure, and many of the kodes from the big versions worked, including the one that gave player 2 25% hp
street fighter alpha - a miracle, with very appealing blobby little sprites with amazing animation
Bionic Commando. This one leans heavy into the bionic stuff, with a lot of futuristic aesthetic instead of world war two part two that the NES title did. And the smaller screen made everything tighter.
Race Driving for the Gameboy was done by the Argonaut folks, who did X, and it looks better than the megadrive and snes versions. A full on 3D race driving sim?!
the Dragon Quest 1+2 & 3 GBC ports are 1:1 the SNESFC versions other than visuals – which are still very pretty and arguably even more charming (the DQ3 character sprites are adorable)
the later GB Mega Man games are basically new games altogether and are pretty cool, in general those ports are decent
GBC Rayman is basically a condensed (and better) version of the PSX game, GBC Rayman 2 is wprse but notable as a weird port of the console games in the same engine as the first
the GBA port of AD&D: Eye of the Beholder is a real oddball, it turns the Dungeon Master inspired real time blobber combat into a turn based Gold Box like