One Time Features
This mode had you completing challenges such as "Get 10 mini turbos" or "Beat Wario to the finish". It was planned to reappear, and it kinda did in Tour, but not quite.
Mission Mode (Mario Kart DS)
Mario Kart Super Circuit
Baby Park
Nintendo GameCube
Block Fort
Battle Map
Despite trying for many years, this player never was able to reach 32/32 world records in Mario Kart 64.
Mathias Rustemeyer
You could link up consoles to play multiplayer in this one, and if by some miracle you had everything needed (4 consoles each with 4 controllers, 4 copies of the game and so on), you could have a 16 player match.
LAN Mode (Mario Kart Double Dash)
A challenge to submit the fastest time trials in this game was run in Japan, where you would send proof to nintendo. All four courses were won by the same guy.
Mario Kart Double Dash
Peach Stadium
Wario Stadium
Race Track
While more known for his youtube content these days, this player actually earned several glitch world records in Mario Kart Wii.
TWD98
This feature only appeared once because it was directly tied to the console itself, but you could receive ghost data, and a custom grand prix, from other players you encounter.
Streetpass (Mario Kart 7)
Yes it's a hunk of plastic, but it's an endearing hunk of plastic. And for a while, you couldn't buy a copy of Mario Kart Wii without one.
Wii Wheel
Vanilla Lake
SNES
Luigi's Mansion
Trick Question: It's Both
Earning multiple world records across multiple games, this Japanese player even appeared in a promotional video for Nintendo.
NOBUO
This feature enabled easy sharing of your races. Unfortunately, it was directly tied to another feature that has not worked for almost a decade. Even stranger, this feature has never reappeared in any port of this game.
Posting to youtube (Mario Kart 8 Wii U)
Nintendo organized several tournaments for this game, and the winners would get a special controller.
DK Summit
Wii
Frappe Snowland
Race Track
This Canadian player implemented many new strats in Mario Kart Wii, from the peach beach glitch to a strat on Mario Circuit that's named after him.
KingAlex
Somewhat similar to another feature, this feature would provide challenges for the player, as well as a leaderboard to aim for. However, these challenges were sent over the internet, one at a time.
Tournament Mode (Mario Kart Wii)
If you bought the bundle of this entry and the console it released for, you would get to pick from one of 4 games, and get it for free after registering it with club nintendo.
Mario Kart 8 (Wii U)
Cheep Cheep Falls
Game Boy Advance
Sweet Sweet Kingdom
Battle Map
This player was briefly the champion of Mario Kart 64 time trials in the early 2000s, but it turned out to actually be 3 people, one of which actually returned to the game a few years later.
Eric Habrich (Luke Barnard and Troy Ullman)