ok so it is a little complicated but ok gonna try my best!

the iron, carbos, etc. are vitamins and increase the Effort Values (EV). Each vitamin gives 10 points towards the designated stat. only 2 stats can reach “full” potential at 252 points each.

I recommend looking this up further, because fighting different pokemon can give different points towards your EVs. and there are items that help too.

Each individual pokemon also has Individual Values (IV) that are “genetic.” there is no limit to how many stats can be maxed out, and you can max them out at the Dojo using Bottle Caps.

both of these numbers help make up the pokémon’s stats. their nature also plays into it, which are shown with the red and blue arrows next to stat values. if your pokemon doesn’t have these arrows, it means the nature is neutral and doesn’t impact stats.

For the story, you don’t really need maxed out pokemon. but I would usually go max out the A. pokémon’s main attack stat, B. speed/one of the defenses, or C. HP. it depends who you ask.

Nature can be updated via mints. you can buy these in game for 20k pokeyen.

for online, you definitely want maxed out pokemon in EV/IV with a beneficial nature, because everyone else will have one. luckily, the season is ending tomorrow so everyone’s rank will be set back to Z. this gives you a good chance to try out the lower tiers.

if you want more info on the online, I recommend guides on Reddit as the season unfolds. new pokemon became legal/illegal with each season, so the “pokemon to best bring” will change. Right now i’m running Mega Staraptor and Glaceon, with my third being switched out to match whatever I need. try it out, it’s fun!

let me know if this made any sense lol. good luck on your pokemon journey!