>>390432071. Pokemon has literally never been a balanced game. Making a balanced game has never been on GameFreak's priority list.
2. Even if we 90% of Pokemon were unusable by meta standards, that would mean that 90% of Pokemon would still qualify for niches in the lower tiers of things like Smogon or even VGC. Hitmontop and Incineroar are complete ass in singles, but in VGC they're incredibly good, with Roar being the most used Pokemon in Sun/Moon VGC.