Sadly, it would.Honestly I wouldn't necessarily call that a bad thing.
Competitive Pokemon is basically like a way more complex game of chess. Rather than "you can only move forward 2 steps", pieces have a bit more options, but those options are relatively limited and predictable, and player skill comes into play when deciding what to pick and predicting the opponent choice.
The more options there are, the harder it gets to predict or even guess what the opponent will be doing, and the game just turns into a guessing.
Basically, it's like if you play battle facilities blind: without actually knowing what the enemies can have, you're literally playing guessing games and either winning or losing because you guessed wrong.
It is counter intuitive, but having a excessively large amount of viable choices is not necessarly good for a competitive game's health.
Eh, there's plenty of fringe options that I don't see balanceable.But all this is of course hypothetical because, as Kurona pointed out, they would need to actually make more changes. Though aside from what I thought, what changes do you think would need to be made to not make Pokemon carrying multiple items not be OP?
Think of setup sweepers being able to carry both a Life Orb and a Lum berry, focus sash or lefties. Or pokemon able to carry both choice band/specs and scarf. Even combos like Choice item + Life orb.
You'd need a significant revamp of the power level of said items to make them not break multiple pokemon and turn the game into a "broken checks broken" scenario where whoever gets the first move wins.
It's similar to Dynamax in singles in a sense: most of the games end up decided on whichever player got a sweeper setup and rolls over the other, rather than actually being able to maneuver.
Edit: in fact, I found a very good example: have you heard of the Rock Paper Scissor Lizard game?
It's a meme featuring Star Wars, but it plays off the fact that
- You pick a relatively fun and easy to maneuver game, rock paper scissor. Opponent only has 3 choices, so do you. You usually have a ~33% chance to guess correctly what the enemy has done.
- There's a intermediate version with 5: this gets more complicate and you already are down to a 20% chance to guess correctly.