It's not a small task, it's a monumental task. I listed examples of existing difficulty features in games and outlined why it doesn't make sense for from games. You're completely missing the point, and willfully ignoring the fact that you are not the target audience.

The reason I even mentioned the mainline Pokemon games is that they aren't for me. They will NEVER add any level of real difficulty to a pokemon game, so it doesn't provide the friction I want in a game. And that's okay. I'm not so entitled or delusional that I think gamefreak should cater to my tastes over that of their existing fanbase, and I'm content to rely on romhacks, mods, and similar titles like siralim to provide the depth and challenge I'm looking for in the genre. "Just add an easy mode" is an asinine take when you imply, like you have here, that it's something the developer could just turn on. It's more like three or four digits of work hours that wouldn't contribute to sales in a meaningful way.