R.O.B.

History:

R.O.B. the robot is an interesting case. Scholars in the Mushroom Kingdom are unsure of where exactly he came from but sources indicate that it is possible that he is a temporarily displaced in his own space-time, similar to how Master Hand is able to assemble fighters for the Super Smash Tournaments. R.O.B. does not originate from the Mushroom Dimension and so has no real ties or relationships to anyone else. He exists only to race, although he had some kind of natural connection to Rainbow Road, perhaps using his temporal displacement to help construct the similarly otherwordly track.

DS:

R.O.B. appears only as an unlockable character in DS for some reason. He really has no purpose being here but nevertheless he provides another good heavyweight character. The system in DS provides three unlockable signature Karts for each character, although every character may use any Kart. These include a standard, one with better stats but a weak Item rating and one with worse stats but a high Item rating. R.O.B. generally has excellent Speed, along with the best Acceleration and Handling of any Heavyweight. He is also tied with Bowser as the Heaviest driver, adding 3.5 to the weight of each Vehicle. This all comes at the expense, however, of his Drift, which is the worst in the game. Take a look:

There are also Staff Ghosts in DS. R.O.B. owns the Desert Hills track for some reason, with a time of 1:31:262 using the ROB.-LGS along with Rainbow Road in the ROB-BLS in 2:16:246. The Rainbow Road here makes sense, R.O.B. is a weird character for that weird track, but the Desert Hills is awfully random. Needless to say, R.O.B. did not make a comeback after this game.

Wario Colosseum

History: 

The construction and use of Wario Colosseum in the Grand Prix has been controversial. In the days of Ancient Mushroom Kingdom, the Colosseum was the site of grand games surveyed over by the King, but in the centuries since its popularity it has feel into ruin and disrepair. Wario was able to use his cash and influence to outfit the Ruins to fit a contemporary sport - Kart Racing. Similar to his insistence on Stadium Tracks where he can sell more tickets for a bigger profit, his Colosseum was meant to house a great number of spectators. This has come as an ire to preservationists in the Kingdom who did not want to see their heralded ruins damaged. Wario also built a track so long and complex that it was decreed by the Grand Prix organizers to be set at two laps rather than three. This is the only track in Mario Kart History to be so adjusted, which Wario always viewed as a slight to his entrepreneurship. This track has not appeared again due to this handful of issues.

Double Dash:

There is a lot to this course. It's similar in theme to Wario Stadium in that it has many twists and turns and curves and is also extremely long. It could actually be interpreted as a three-dimensional version of that course. There are many straightaways, boost pads and a wide collection of 90° turns. It's a jumbled mess and a difficult track to come back on if you fall behind. Someone maneuverable is vital but it is also a pain to lose a close photo finish on that final straightaway.


There are also Secret Staff Ghosts on every track in Double Dash. For Wario Colosseum the Staff Ghost is Wario with Waluigi in tow cruising around in the Wario Car. They finish with a time of 2:21:106.

Dry Bones

History:

As Lord Bowser and his Major Domo, Kamek increasingly experimented with Dark Magic, they became obsessed with ideas of immortality. As Bowser encountered King Boo in the Boo Woods his interest turned not towards extending life but towards defeating Death. After countless Dark Magic trials on the innumerable Koopa Bodies robbed of life by Mario he perfected his skeletal fighting force - the Dry Bones. They aren't exactly zombified flesh-eaters but rather reanimated bones heavily resistant to heat and physical damage. In an effort to create a more loyal follower than Koopa or Paratroopa to race alongside him, Bowser invited the most worthy Dry Bones to race in the 2005 Grand Prix and he has been there ever since.

DS:

Dry Bones debuted as the only Lightweight Secret Character in DS. That game has an interesting system. Each Character slowly unlocks Three Signature Karts with varying stats - one average, one worse, but with a good Item Rating, and one that's excellent but with a low Item Rating. Eventually though, all Twelve Characters can access all 36 Karts, making for a crazy amount of combinations. Characters in different Karts don't change stats besides their initial Weight Class. Dry Bones adds nothing to the weight of any Kart, making him the Lightest in the game. Dry Bones' initial Kart Offerings are thus:

His Acceleration and Handling are among the best in the game. In fact, the Dry Bomber is the only Kart with a perfect 10 in both of those categories. His drift is slightly below average, but his speed is really awful. The Banisher has by far the Worst Speed in the Game. Still, the Dry Bomber is an excellent choice for anyone in Grand Prix.

Dry Bones' Ghosts in every game have only featured on Retro Tracks. features as a Staff Ghost on two Courses. He finishes the Donut Plains 1 with the Dry Bomber in 1:08:027, possibly alluding to his dryness. He's also in the 64 Banshee Boardwalk with the same ride in  2:14:403, a clear reference to his spookiness.

Wii:

Wii featured Three Size Classes who each had access to Six Karts and Six Bikes of varying stats. Each Individual Character also has his or her own Bonuses that add to certain stats. Dry Bones again has an Acceleration Bonus as well as a Drift Bonus but he really excels at Mini Turbo. His +6 is tied for the highest in the game and when using the Bullet Bike he ties with Koopa as the highest Mini Turbo Stat available. Here are his specific Stats:

The Bullet Bike is also the closet thing he has to a Signature Kart because its colour scheme fits Bullet Bill's actual colour scheme when Dry Bones uses it. You should use that Kart with Dry Bones for sure, it's one of the better Small Vehicles and Dry Bones makes it better. His Bonuses favour a very specific style of play, though, one that relies on managing tricky turns and corners with plenty of drifting and control. It can be advantages for complex courses in the hands of experienced racers.

His one Ghost appears in the Retro Desert Hills. Not only is it a course from his original Kart Game, DS, it's a very dry course. Dry Course? Dry Bones. It's all coming together. The Normal Ghost uses the Standard Bike S in 02:10.233, the Expert upgrades to the Tiny Titan in 01:52.686. That Kart only nominally takes advantage of Dry Bones' Bonuses. Switch to the Bullet Bike and take him down.