Pokemon started becoming shitty when they began putting the battles above the story. The battles should be a medium through which to further the story and focusing on developing them around the multiplayer competitive circles was a mistake.

Pokemon started becoming shitty when they attempted to reboot the series and ended up creating over one hundred new pokemon that were redundant and attempted to allude to gen 1 pokemon, most of which are still over shadowed by their original counterpart and now only exist as clutter the games have to continue including.

Pokemon started becoming shitty when they decided to toss the adventuring and strategic party building aspects of HMs instead of developing a better system or powering up the moves in battle. Every RPG makes you choose between battle power and out of battle utility, and finding a balance of that in your party in order to explore the in game wilderness enriched the experience.

Pokemon became shitty when the "Pokemon with Jobs" became the norm. Having a few humanoids who were psychic or fighting was fine, but making the more animalistic animals also humanoid such as Watchog for example makes immersion in the pokemon world harder to achieve.