Turok: Rage Wars (Bit Managers/Acclaim Entertainment, 1999)
I've seen this game on some other people's "best of" lists, and I have to assume that was because of the fantastic music and decent graphics rather than the awful gameplay. This first level goes on for ages without ever changing, and none of the enemies pose any threat as long as you let them come to you and then stab them. You have other weapons, but the knife is a OHKO and there's no reason to use them. The second level's clever idea to shake things up is to become an auto-scroller, which does not help.
Turok 2: Seeds of Evil (Bit Managers/Acclaim Entertainment, 1998)
The first Turok to release on GBC had more varied backgrounds, but worse music and abysmal gameplay. The humans here all look the same, but some of them are randomly hostile and you can't fight back. Eventually you'll make it into a warehouse with grey dinosaur people, who are always hostile but still immune to damage. If you die there, you go all the way back to the beginning of the level. It's awful, and I don't understand how anyone thought that design was okay.
Turok 3: Shadow of Oblivion (Bit Managers/Acclaim Entertainment, 2000)
It reuses a ton of assets from the first game and inherits its problem with forcing an extremely slow pace. If you try to go quickly at all, you will take damage. The only way to be safe is to freeze every time you see an enemy start moving and hit them as they come to you. The second level also throws in pitfall traps to really emphasize that you're meant to walk very slowly.
Tweenies: Doodles' Bones (Tiertex/BBC Multimedia, 2001)
It's a Tiertex game, so it doesn't start.
Tweety's High-Flying Adventure (Kemco, 2000)
A puzzle platformer where you need to beat up Sylvester in order to beat each level. The graphics are terrible, but it was modern enough to have a tutorial and the gameplay is at least fairly original.
Uchuu Nin Tanaka Tarou de RPG Tsukuru GB2 (Enterbrain, 2001)
Another RPG Maker for GBC, but now with a couple of basic example RPGs built in. I'm still not really sure why you'd want RPG Maker on a handheld with no way to transfer your work to anyone else.
Ultimate Fighting Championship (Fluid Studios/Crave Entertainment, 2000)
A fighting game has movement towards and away from the camera even though it's really hard to tell which plane your fighter is in and using that movement results in a lot of comical missed punches and kicks. Health regenerates slowly for both you and your opponent and none of your attacks do much damage. The only way I could make any real mark was to press A and B together to tackle my opponent and then punch him to death while pinned. I wouldn't call that strategy very fun.
Ultimate Paintball (Morning Start Multimedia/Majesco, 2000)
Despite the name, this has almost nothing to do with paintball and would be better thought of as a collection of randomly triggered shooting gallery minigames. It's boring.
Ultimate Surfing (Act Japan/Natsume, 2001)
A surfing racing game, which sounds like it'd be fun even though surf racing is not a thing. Unfortunately, there's very little space to maneuver on the wave and bumping into an AI player at all puts you, but not them, into this annoying flashing state that makes you slower and harder to control. The whole race is just alternating the dpad up and down while hoping to avoid collisions, which is frustrating and also irritating for your thumb.
Uno (HotGen/Mattel Interactive, 1999)
If you're the one person in the world who enjoys Uno for any reason other than screwing over real people, this is the game for you! You probably don't exist, though.
Vegas Games (Digital Eclipse/3DO, 2000)
A bunch of casino games accompanied by mediocre graphics and sound. The only thing that distinguishes this from the other casino collections is that it has an extremely confusing main menu.
Vigilante 8 (Vicarious Visions/Vatical Entertainment, 1999)
I think this is actually the first car combat game I've seen on GBC, which means there's a good chance it's the only one. Unfortunately, it's terrible. Holding the gas with B while also shooting with A and turning with the dpad feels awkward, both cars have 10 times more health than they should, and I ended up getting caught on the geometry and trapped right as the AI was down to its last pip of health. But then the AI was so bad that it couldn't hit me, so it probably would've been a stalemate forever.
VIP (Planet Interactive/Ubisoft, 2001)
This game is infamous as a "funny bad" title on other platforms, and it probably would be on GBC as well if you weren't playing it. Roller skating while a guy in an ice cream stall throws cones at you is probably the most 90s thing ever despite this being a 2001 game, but the humor doesn't land quite as well when it takes at least 15 seconds for your character to stand up and even random balloons inflict the same penalty. Other levels have you playing different minigames, but they're all bad.
V-Rally: Edition '99 (Bit Managers/Infogrames, 1999)
As much as I've ragged on Outrun-style games like this over the past 73 parts of the series, this one is actually good. The sound effects can still be a little annoying, but they're the best I've heard on GBC, and the track manages to be interesting while still giving you time to make turns. I'm not sure if it'll work as a streaming game, but I'm going to toss it on the list anyway because I'm curious to see how it holds up on later tracks.
Wacky Races (Velez & Dubail/Infogrames, 2000)
Unfortunately, this game is racked by visual glitches that make it basically unplayable, but even with those issues I can tell there's a surprisingly great game here. It's in the style of Mario Kart, but, at least from the little bit I was able to play, it might survive a comparison to that game's GBA outing. I'm going to put it on the list in the hope I can find a working way to play it, but there's a good chance that won't happen.
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
V-Rally: Edition '99