What do we know about how NPC move choice is randomized?
I know we know a lot about overworld stuff like when random encounters happen…
If it's the same in FireRed and LeafGreen as it is in Red/Blue/Yellow, then it's all about how long we wait in the move selection menu?
As it says for FRLG:
At the start of the game, RNG goes forward at two per frame in battle, and one per frame outside a battle. This means it’s possible to switch the parity of the RNG by delaying one frame before starting a battle, but it’s not possible to control this parity later, meaning you would be forced to skip some RNG values that you may have want to use (a RNG that determines a critical hit earlier, for example).
Looking at other TAS commentaries, like for Red, Green, Blue, Yellow, or looking at the disassembly might help?
Best Answer
TAS Videos on Pokemon Gen 1 Luck Manipulation says:
So, if I'm reading this right, a summary is: If you have a save state and you wait and/or hold down the attack confirmation key press for different amounts of time, you'll probably get the enemy to use different moves, unless their AI locks them into one "perfect" choice like the well-known Rest Forever Lorelai with Dewgong.