King Boo

History:

Centuries ago a Great King ruled over the Koopa Kingdom. He died in a Great War with the Mushroom Kingdom but his soul was unwilling to pass on. He became one of the Boos, and tho he forgot his past life he still contained great power within him and the other Boos tended to follow his lead. Now fearless and immortal, the King held up in Boo Woods eventually strengthening it as a Ghost Stronghold. He has a loose relationship with Lord Bowser, sometimes allying troops for a common cause but swearing no allegiance. He is also friendly with Petey Piranha, who seeks to become the King of All Piranha Plants like King Boo did with the Ghosts. Finally, he detests Luigi, mostly for his part in kidnapping the Boolossus, one of the King's loyal followers.

Double Dash:

King Boo first appeared in Luigi's Mansion and then made his first racing appearance in Double Dash a few years later. He's an Unlockable Character who partners up with Petey Piranha. The game focused more on Kart Differences rather than Driver Stats, although each Racer has his or her unique Special Item as well as a signature Kart. King Boo is a Heavyweight despite really being floaty and weightless, and drives the Boo Pipes, which is one of the Best Karts for Grand Prix in the game.

The Boo Pipes are the third heaviest Kart but otherwise act like a Light Vehicle. It has very fast Acceleration, 6th in the game overall and First by far for the Heavy Karts. It also has one of the Best Offroad Speeds in the game, again First among Heavies by far. It also has the Best Shocks in the game, meaning that it's not going to bounce around and lose speed on courses with tons of hills like DK Mountain or Waluigi Stadium. Its only faults is the relatively low top speed, at 56 mph it's the worst among Heavy Karts and fair inability to maintain speed through turns. In general though it's big and stable enough to catch a lot of speed early and not be completely wrecked while driving a Grand Prix. It has every feature of a Light Kart without the weight issues, which is far better than the Barrel Train, which is a Light Kart that acts Heavy.

Boo also has one of the best Specials - he gets a Random Item based on his position on the course. If you're in Last place you'll get Chain Chomps and Golden Mushrooms, First will get Giant Bananas and Bob-ombs and so on. This way Boo tends to be successful no matter where he is, meaning he's one of the better Racers for Grand Prix. He also takes up less screen space than Petey, meaning he's basically the Best Racer in the game. Pick Boo. As a Secret Character he has no Staff Ghosts.

Wii:

After a break and not appearing in DS, King Boo returns in Wii. This game featured Three different Size Classes of Eight Drivers each. All of these Racers then had access to Six Bikes and Six Karts each with varying stats. In addition each Character added certain Bonuses to each Stat, making for a dizzying number of possible combinations. King Boo is a Large Character again and gets a +5 Handling Bonus, which is beaten only by Baby Mario as well as a +3 Offroad Bonus. Here are King Boo's specific Stats:

King Boo doesn't really drive like a normal Large Character with High Speed or Mini Turbo. There are a few Vehicles that play to his strengths though. The Offroader and Wario Bike both offer high Handling and naturally, The Phantom works with him to take some sharp corners. He is also good with other Vehicles like the Flame Runner, though, because his high Handling counter-balances its originally awful Stat. In general though, King Boo is far from as dominantly awesome in Grand Prix as he was in Double Dash and there are some better choices out there.

He has a single Staff Ghost who calls the Retro Ghost Valley 2 from SMK home. The Normal Ghost goes 01:06.595 in the Standard Kart L while the Expert upgrades to the Spear in a blistering 00:58.907, which is the Fastest Ghost Time in the Game and the only one under Sixty Seconds.