Going by DLC Pack Tradition (as far as we know) Let's Speculate DLC Pack 3
Usual Status Quo;
1/2 New Racer(s)
Other Slot(s) filled in with Veterans/Clones (Tanooki Mario is an example)
8 Tracks (2 Cups)
4 Karts/Bikes/ATVs
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My DLC Pack
CHARACTERS; King Boo, Bowser Jr. & Kirby
KARTS; Barrel Train [From Double Dash] (unless it's Confirmed), Pipe Kart (Petey Version) [From Double Dash] (Unless it's Confirmed), B-Dasher MK II [From MKWii] (Unless it's Confirmed) & Cheep Charger [From MKWii] (Unless it's Confirmed)
CUP 1; Course based off Mario Sunshine, DS Luigi's Mansion, GCN Baby Park & Course based off City Trial
CUP 2; I have no idea