Hey YoshiMaster, that was a really old track listing, I think we've moved on quite a way from there, here's my take at the current state of affairs:

(but of course Q has the final say)

Luigi Circuit ® MK Revolution Challenged by Gunslingers
Moo Moo Meadows [µ?] ~Unity~ Available
Mushroom Gorge [TGS] The Greatest Superlatives Available
Toad's Factory Koopa Klan Available

Mario Circuit [UKE] UKelites Available
Coconut Mall [§] Sacred Society Available
DK's Snowboard Cross / DK Summit [TGS] The Greatest Superlatives Available
Wario's Gold Mine [TGS] The Greatest Superlatives Available

Daisy Circuit [UKE] UKelites Available
Koopa Cape [AF] Areo Falcons Available
Maple Treeway ® MK Revolution Available
Grumble Volcano [TGS] The Greatest Superlatives Available

Dry Dry Ruins [MKR] Mario Kart Racerz Available
Moonview Highway [xA] Xtreme Alliance Challenged by [TGS]
Bowser's Castle [µ?] ~Unity~ Available
Rainbow Road [rT] Rogue Titans Challenged by [xA]

GCN Peach Beach [TB] Team Blaze Available
DS Yoshi Falls [MKR] Mario Kart Racerz Available
SNES Ghost Valley 2 [MKR] Mario Kart Racerz Available
N64 Mario Raceway *NKS New Killer Stars Challenged by [xA]

N64 Sherbet Land [§] Sacred Society available??
GBA Shy Guy Beach S* SilverStar Available
DS Delfino Square ICE* Invitational Clan for Excellence Available
GCN Waluigi Stadium [MT] Mushroom Team Available

DS Desert Hills [TGS] The Greatest Superlatives Available
GBA Bowser Castle 3 tP Team Prime Available
N64 DK's Jungle Parkway [§] Sacred Society Challenged by Unity
GCN Mario Circuit [TGS] The Greatest Superlatives Available

SNES Mario Circuit 3 [MT] Mushroom Team Available
DS Peach Gardens [xA] Xtreme Alliance Available
GCN DK Mountain [yE] Young Elites Available
N64 Bowser's Castle ® MK Revolution Challenged by [KK]


I don't know the state of the challenges that were in progress