"Pokemon got easier" is a myth, the older games were even easier than the newer games. They are probably slightly harder today than they were in the old days. The big deal is that in the old games the enemy trainers had much worse teams than they do in newer games. Generally speaking, it was only at the very, very end of the game that even boss trainers stopped using not fully evolved Pokemon, and the movesets on enemy Pokemon were just so consistently bad. In modern games, boss trainers after the earlygame use only fully evolved Pokemon, and the movesets tend to be filled with good damaging moves or support moves that actually make sense in the context of the team. Like seriously, just consider these two Pokemon and movesets:

Gen 1 Champion Blue:

Rhydon
>Leer
>Tail Whip
>Fury Attack
>Horn Drill

Gen 8 Champion Leon

Dragapult
>Shadow Ball
>Flamethrower
>Thunderbolt
>Dragon Breath

Just seriously, with a full game to prepare, that Dragapult is entirely reasonable to deal with, but it probably can and will super-effect most of your team. That Rhydon almost literally can't do damage to any vaguely useful Pokemon (remember in gen 1, Horn Drill can only hit Pokemon equal or slower in speed to the user, and Rhydon is a very slow Pokemon).