Level 3-6 (Mario vs. Donkey Kong: Tipping Stars)
From the Super Mario Wiki
The toys start on two different storied platforms at the right side of the course. However, Mini Toad is initially blocked by a wall of Blue Color Blocks. Mini Mario has to use conveyors and Red Girders to climb up to a Blue Color Switch and press it to free the Mini Toad. Both toys should then be escorted through another series of conveyors and Red Girder Rivets to the Goal Door on the far left.
The M Coin is located in the left half of the course, near the Goal Door. It is found on a platform right above the door, behind a wall of Blue Color Blocks. To reach it, the Minis should first disable these blocks, then climb to the coin using Red Girders.
The following data applies in both the Nintendo 3DS and the Wii U versions of the game.