330 hours.. i didnt "just start playing". And no, you cannot evolve them... they require an insane amount of experience to level if you evolve them. You get set super behind in levels in comparison to trainers and gym leaders in your current area, and it is impossible to level them up because the pokemon in the wild around said trainers and gyms are very low level and give very little experience. To put it into perspective since clearly the inexperienced player here is yourself, take a look at the information below.
Magikarp has a base experience of 20 and Gyarados a base experience of 214. Without even calculating, you can already assume it is 10x harder to level Gyarados than Magikarp.
Also, when I was leveling my Magikarp to 100, at lv 95+ he still only needed sub 1 million exp per level. A level 56 Gyarados I had in my PC still needed around 4 million exp to get 57.
And since it is not recommended to evolve them, why not put a big fat warning sign at the beginning of the game. I've read multiple people's post inside the game in "help" chat talking about how they are stuck and when you ask them what pokemon they have, it is always an evolved pokemon. Of course they're stuck. They're probably 15-20 levels below where they're supposed to be. But hey, they wouldnt even know what level they need because the gym leaders have ?? as their Pokemon levels.
My point is, the game is super punishing for new players. There is one NPC i believe it's in Pewter city that will warn you about pokemon needing more exp per level if you evolve them, which is nice, sure. But why not have Professor Oak tell you who is the first NPC that gives you a pokemon? Alternatively just put a big warning sign the moment someone logs in for the first time. You were never punished in regular pokemon games for evolving your pokemon, and don't even try to say it's not a punishment when 99% of the player base refuses to evolve pokemon pre lv 95. The system is not balanced, and it keeps players away from the game.
https://prowiki.info/index.php?title=Experience_System