I honestly don't understand how levels work in the anime. Sometimes it seems like it doesn't matter at all. But in one early episode, when they come to an academy, a student there comments that Pikachu should be at level 25 since they had been training for a month or so but that Ash hadn't gotten it quite that far.
Trying to understand the technical aspects of Pokémon in the anime is futile. I know, I've tried.
You just gotta enjoy the show, not the inner-workings. Anime =/= Games.
But since I need to buy the booster packs to get the codes to play online,
There's a gameboy game, hm? With an actual storyline? Might be worth trying if I can get my hands on it ^^