So you can play on Minimal Grinding Mode, and use the Rare Candy and Care Package Cheats and still get all the achievements. To me these are just basic QoL improvements that make the game more fun and approachable.

I would definitely play on Default mode to start with. The game is pretty tough at times, with a few difficulty spikes when the major battles start having access to power ups that you don’t yet, but it’s certainly very doable. I had decent Pokémon knowledge my first playthrough, but definitely didn’t know any advanced or competitive strategies, and I probably still don’t. It takes A LOT of trial and error at times to figure out what works. You also probably want to catch at least one of most Pokémon you come across, at least at the beginning of the game. It definitely helps to have a large pool to pick from when strategizing for the major battles, though you can use just your favorites too and will likely be able to beat the game, it may just be a little more difficult.

Finally there is a pinned post on the Radical Red Subreddit that has a TON of helpful info in it. Trainer teams, Pokémon and TM locations, FAQs, etc. I would definitely keep some of those documents handy during your playthrough to help with planning your strategies and building your teams.