Unsolved single-goal challenges

As requested by Pannen, here are some ideas of cool things that may be possible, but haven’t been achieved in practice.

Clipping from the bottom area of Wiggler's cave to the top area, or vice versa
Grabbing Ukiki without pressing B
Collecting WMotR Capless and/or Cannonless
Transport cloning with Wiggler or Skeeter
Pulling off a transport clone with 4 simultaneous pushers
Picking up the cannon bob-omb on the same frame as leaving its radius
Collecting the new impossible coin
Killing the mystery goomba and collecting its coin
Collecting the red coin in BitDW at the start without using the ! Switch
Getting infinite coins in CCM
Cloning in LLL (maybe with fall damage instant release via falling from HSF)
Getting the TTC upwarp
Moving during timestop in JRB (to get shell clones)
Grab a bob-omb fake during boiling
Vertical PU death in LLL
HSWK between towers in TotWC
Crashing the game by triggering death barrier before activating the TotWC starting textbox
Putting the Ukiki that steals your hat on the monkey cage, so the Ukiki that opens the cage will murder the other one
Bring the mama penguin to the bob-omb buddy to trigger text glitches
Survive in a vertical PU with a shell clone released in it
Walking around in SA by glitching the water by punching the n64
Beating as many IL stars as possible while crawling the entire time
Collecting the BitDW key from underneath the ground, causing you to collect the key on the death floor
Speedrunning levels with the joystick stick in a set position, only changing angle via camera buttons
Using a hacked save state without water and getting the star in SA without water

Some challenges formerly listed here have been accomplished. Here they are: