>>31461498It wouldn't destroy the game, just make it a very different one.
For a start, it'd remove any decision making process over moves, what coverage to have, how many STAB moves etc.
This would a. make all pokemon functionally the same. You wouldn't have a unique moveset built for a purpose, because everyone had all the moves all the time.
It'd also remove a lot of the guessing and risk against an opponent. You KNOW they have the move, the only question is whether they've statted to use it optimally.
It'd also remove any ability to PP stall moves. Plays like "If i let X die to Fireblast, then Y will be home free", because, well, they'll probably have a back up. Especially if it's STAB.
Any set up plays would be gone, because almost everything would have taunt or phasing, moves that will often be on only one specific pokemon.
And of course, larger move pool mons will gain a massive advantage over lesser ones. Haxorus LOVES having both dances, the option between Dragon Claw AND Outrage, checks left depending AND all it's coverage moves.
Something like Talonflame or KlingKlang... it's got very little else TOO run outside about 5 moves. They're entire plays will become entirely predictable.
TL;DR:
No more suprises
No more individuality
No more strategic stalling
Set up is severely diminished
Powerful mons get coverage for ALL the things.
Shallow movepools kill the mon,