XxsomethingX

Atm, I'm using Mario with a bike. But I haven't unlocked every car/bike yet.

Any recommendations for bikes and/or karts I should unlock?

Also, do different characters have different stats for racing? I've heard Waluigi is faster than most characters.

Exceltor

Diferent characters change stats, but only a bit, not much.
Online I use the initials bikes, specifically Bowser Bike with Funky Kong. I have only have used unlocked bikes to test them.

duckwilliamson

Online I prefer a really fast recovery over anything else ... hence I use Dry Bones + Magikruiser (both unlockables)

-Wolf-

I race with Dry Bowser (Large) in Twinkle Star

[µn]Pikadoodles

Funky Kong + bowser bike.

cam

Mii and bowser bike

[Bowser]

Dry bowser with Dragonetti or the Standard kart is the bestone :}

Acww52

I use rosilla and stander bike

Man Bear Pig

Different characters do not have different stats, it's all about the car.

I use Luigi xD

Hooktail

First Try mastering Inside Drifting.
Then use Bullet Bike (Light) Mach Bike/Dolphin Dasher (Medium) or Bowser Bike (Heavy)