Official Pokemon games have always been, and always will be, designed to be beatable by children who only need to understand maybe a third of the mechanics. For example, I’m pretty sure most 10yo kids couldn’t tell which types used Atk and which used Sp. Atk, before the split, but despite that, we beat the games anyway.

If you want a challenge, or any semblance of balanced mechanics (level caps to temper the forced EXP share, smart AI that takes advantage of switching and hazards, having every battle focused around doubles, etc.), then you should just play ROMhacks instead. They’re far better than the actual games nowadays.