Transform empty move glitch

The Transform Empty Move natural glitch which can occur in pokemon Red Blue or Yellow.

Description

In Generation I, the moves Mirror Move and Metronome draw 2 PP from their assigned slot when used. To "fix" this, the game also adds 1 PP from the assigned slot, however when it does this, it ignores Transform.

Normally when a pokemon uses Transform the pokemon's PPs draw and add from 4 new slots, separate from the pokemon's normal moves. Because Mirror Move and Metronome add PP to the non-transformed slots, this can cause extra PP to be added to slots that have no moves (in Ditto) or it can add extra PP to push an attack past the cap (in Mew).

This can cause Struggle to be unusable even when Transform, Ditto's only attack, is out of PP. If disable is used in this state it can also softlock the game. This cannot be fixed by healing at a pokemon center, or similar place since the game doesn't decrease PP when healing.

In a practical note, this could be used to push Mew's non-transform moves's PPs far above the cap, up to 256. To fix a ditto trapped in this state, the user will have to repeat the glitch 256 times, to overflow the PP back to 0.

Credits: Crystal_