Finding the Pit of 100 Trials in Super Paper Mario: It's in Flipside, Not Flopside

The Pit of 100 Trials is located in Flipside (the "light" dimension), not Flopside (the "dark" mirror dimension).

Access

1. Go to Flipside 1st Floor (main town square).
2. Find the door in the center of the floor (between the two staircases leading to B1 and 2F).
3. Enter. It's a 100-floor gauntlet, no saving, no items (except what you carry).

Requirements

• Beat Chapter 7 (unlocks Flopside, but Pit is in Flipside).
• High HP, good healing items, strong attack (Carrie, Bowser, or Luigi with Super Jump).
• Return Pipe (found midway) lets you exit and re-enter at that floor.

Reward

Treasure Chest with 9999 Coins (or Shroom Steak in some versions). Bragging rights.