For everyone struggling, here, some advice:
1 - Before you leave the house, pick up the potions from your computer (withdraw).
2 - Before you leave the house, pick up the leftovers from your room and give them to your pokemon.
2.5 -If you struggle in fights, either use double-team or potions. (the latter is the better)
3 - Buy 5 Fresh Water (and only that) at the vending machine. If you run out of potions or water, always restock here, don't buy overpriced potions at the market.
4 - Buy 5 Pokeballs at the market.
5 - Make sure to bring your pokemon to lv 10 by grinding some encounters in the village-grass.
6 - As soon as on route 1, get into the grass and look for the oddish Lv 11 - capture it, it will be making things a lot easier later on in the game, trust me.
7 - Bring your oddish to at least lv 18 in this area while swapping pokemons in fights and defeating the hikers graveler and the girls pelikan.
8 - Catch the mightyena with the megaball from the hiker's location. Make sure it's a female with intimidating. Use oddish's sleep powder, if needed. (This will take a lot of tries, most likely - but it's worth it, trust me. - Save right infront of it and then use f12 everytime it's not female with intimidating)
9 - Get the bunny and get it to evolve and join your team (very strong pokémon).
10 - Make sure to level-up all 4 of your pokemons at the same pace.
11 - If you run into problems, make sure to check which of your pokémon's attacks is the most effective against whatever you're dealing with. And if the problem persists, go and grind 1-2 levels in the local grass.
You won't struggle from here, following this.