Tiger Woods PGA Tour 2000 (Xantera/EA Sports, 1999)
It seems surprising that this came out in Europe before North America, but less so once you consider that the interface is more complicated than your average German mechanical simulator. Underneath all that messy UI, though, it's really just another golf game.
Tintin: Le Temple du Soleil (Bit Managers/Infogrames, 2000)
A crappy puzzle platformer. The girl playing with a yoyo right there will do damage to you, and she can't be jumped over. The game wants you to learn that you can move into the background to get around her. That mechanic is much less fun than jumping over enemies, but it's not like anything else about this was very well done either.
Tintin in Tibet (Bit Managers/Infogrames, 2001)
For some reason everyone starts throwing packages at you when the train reaches a dead end. The dead end is because the tracks have fallen away over a canyon, and you need to platformer over it. If you fall in anywhere, you start the level over from the beginning. It's a much better game than the last one, but it still isn't fun.
Tiny Toon Adventures: Buster Saves the Day (Warthog/Conspiracy Entertainment, 2001)
You need to throw those burger things so that they bounce around and hit enemies, who you can then walk up to and kill. Do that to all of them and the level is over. It's not a particularly fun mechanic, and the reuse of backgrounds and music with only a different pipe layout to distinguish levels does not help.
Tiny Toon Adventures: Dizzy's Candy Quest (Formula/Conspiracy Entertainment, 2001)
You need to move around this maze and collect candy for the robot. Stepping on a star tile gets you extra points, but if you fall into one of the many traps, all your candy goes back to its spawn position. It might've been an okay game without that frustrating mechanic, but with it it's just bad.
Titus the Fox (Aqua Pacific/Titus Software, 2000)
A port of an Amiga game from 1992 that was itself a reskin of a 1991 game that Titus decided would be better with their mascot. Its Amiga origins explain the terrible graphics and three second music loop, but that's no excuse for not updating either of those for the GBC release.
TNN Outdoors Fishing Champ (Starfish, 1998)
This is the US title of the sequel to Super Black Bass Pocket 2, which came up a few posts ago. It's mechanically very different, but that's not enough to save it from being boring like all the other GBC fishing games.
TOCA Touring Car Championship (Spellbound Interactive/THQ, 2001)
It actually feels and sounds quite good, but it desperately needed a map so that you have any way of telling when turns are coming up. I think they meant for the track signs to cover that, which would be fine on any other system that had high enough resolution to actually read them at speed. Unfortunately, that one problem sinks what otherwise might've been a fun racer.
Toki Tori (Two Tribes/Capcom, 2001)
A puzzle platformer where you have to collect all the eggs in the level as quickly as possible. It plays pretty well, but there's no reason to come back to this version when it was ported to just about everything that was out by the mid-2010s. It is notable for being the only GBC game I've seen that has Japanese and Western languages on the same cart.
Tokimeki Memorial Pocket: Culture Hen: Komorebi no Melody (KCEK/Konami, 1999)
A Princess Maker-style life sim in which you play as a high school student. In an unusual twist, you can lose stats if you fail at a training task. That's not exactly fun.
Tokimeki Memorial Pocket: Sport Hen: Koutei no Photograph (KCEK/Konami, 1999)
I expected "Sport Version" to be the same thing but with a student athlete, but it's actually just completely the same thing. I assume the prologue that I skipped for time was different between the two games, because there certainly aren't any other differences in the early stages.
Tokoro-san no Setagaya Country Club (Natsume, 2000)
A golf game that is notable both for its "sabanna" course and for the lack of a timing mechanic on your swing. You can freely set the hit point and power to whatever you want, which would trivialize most courses once you got a feel for them. Still, I think I prefer this to the massively overcomplicated interface from the Tiger Woods game above.
Golf Ou: The King of Golf
John Romero's Daikatana
Kakurenbou Battle Monster Tactics
Keitai Denju Telefang
The Legend of Zelda: Link's Awakening DX
The Legend of Zelda: Oracle of Ages
The Legend of Zelda: Oracle of Seasons
LEGO Island 2: The Brickster's Revenge
Metal Gear Solid
Millennium Winter Sports
Pokemon Crystal Version
Pokemon Card GB2 - GR Dan Sanjou!
Pokemon Puzzle Challenge
Pokemon Trading Card Game
Quest for Camelot
Return of the Ninja
Scooby Doo! Classic Creep Capers
SD Hiryuu no Ken EX
Shin Megami Tensei Devil Children: Aka no Shou
Space-Net: Cosmo Blue
Star Ocean: Blue Sphere