Any suggestions for a newbie here?

Not exactly newbie, since I completed two regions.

My question is, how do I improve competitive wise? For the past 9 years, Having played Main Games and fangames/rom hacks, I have always been the type of player to focus only on story of Pokemon games, rather than taking them competitively. Pokemmo has shown me my current level and knowledge at this point, and it really feels disheartening. Even post game battles in Kanto and Johto rather feels difficult, even with a good team and balanced EV spreads. Is their anyway to reset their EVs? Also, how can I think of Pokemmo more competitively? Should I invest my time more on Gaining Pokemon knowledge and their setups?