Last published challenges
Drinking some "Protein Drinks"
Fourside : Go to Jackie's Cafe.

...So where exactly do you fight in Smash?
Fourside : Go to every intersection.

I couldn't find an image of the Hint Man on WikiBound, so I used the next best thing.
Fourside : Go see the Hint Mr. Saturn.

Rocky Hills Run
EKDS Rocky Hills : Complete the track in less than 1:50 in Time Trial mode

is this my first battle challenge?
Survive more than 3:00 with 1 balloon or more, without drifting, without touching item boxes, without using any item

Sherbet Land : Complete the track in less than 1:40 in Time Trial mode

Équerre
GCN - Piranha Pipe Slide : Complete the track without touching any chèques

Encuéntrame...
Dragon Boy's Rest Valley : Encuentra mi cuerpo corrompido tras quedar atrapado en este videojuego... with King Boo

Sherbet Land : Collect all coins in Time Trial mode, without touching any Freezies, with Rosalina, in less than 1:00

Coin Grubber
Thwomp Circuit : Collect all coins in less than 30s
With 8 participants

why do we exist?
baguette : Complete the track in less than 1:10 in Time Trial mode, without using any item

Luigi´s Practice
GCN Luigi Circuit : Complete the track in less than 1:50 in Time Trial mode, with Luigi
No teams

Time trialer
a simple time trial course : Collect all coins

Coins in Battlefield
SNES Battle Course 1 Race : Collect all coins in Time Trial mode, in less than 3:00

Chaos Zone
Coin cup : Make at least 8 points in 1 race in VS mode, with 19 participants

Survive!
Toadstool Titan a.k.a Mush Pit : Survive more than 1:00 with 4 participants

sands
GCN MegaloYoshiCircuit : Finish in the 1st position in VS mode, without touching any bone, by falling at most 1 time

Break The "Bricks"!
Toadstool Titan a.k.a Mush Pit : Hit all item boxes with 4 participants

You Are Rewarded With 10 Coins!
Toadstool Titan a.k.a Mush Pit : Collect all coins with 4 participants

You Have Been Cursed By The Reverse Mushroom!
Toadstool Titan a.k.a Mush Pit : Finish the game in the 1st position with 4 participants, by driving backwards
