Unsolved single-goal challenges

This is a list of single goal challenges that are incredibly difficult/impossible with current knowledge. None of these have been completed.

Clipping from the bottom area of Wiggler's cave to the top area, or vice versa
Grabbing Ukiki without pressing B (useful for the BBC)
Collecting Mystery of the Monkey Cage without changing the HOLP for an arbitrary HOLP
Collecting Wing Mario over the Rainbow Capless and/or Cannonless
Transport cloning with Wiggler or Skeeter
Performing 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 (THI)
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)
Reproducing the TTC upwarp
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
Survive in a vertical PU with a shell clone released in it
Collecting the BitDW key from underneath the ground, causing you to collect the key on the death floor
Collect a star during a demo sequence
Activating 4 or 5 stars at once in BoB
Activating more than 4 stars at once anywhere
Reversing the one-way teleport in THI
Ground-pounding Chain Chomp's post without interacting with the red coin (e.g. collecting its two coin value)
Escaping from one of the fish tanks in the JRB room (starting with zero speed and damage counter)
Get back on the platform after falling off in the Bowser 2 fight