Things You Should Have Before You Get Into Competitive Pokemon Battling
The most common mistake of new competitive players is that they have a team of all sweepers, which is not that bad in a few cases but most of the time it is. Walls are Pokemon that eat up hits like Rotom Wash.
Oh so fun to utilize, but awful to face.
The reason I'm allowing surf on a Pokemon is cause it's powerful, but even then it loses it's potency to moves like hydro pump and scald
These will definitely be the most important to understand before going into competitive battling, because you probably wont be used to utilizing them to their full potential in the games.
I know this sounds silly, but (at least for me) this relaxes me and takes of the pressure of misclicks. My playlist consists of song like Welcome to the Jungle, Back in Black, and Aces High
Whenever you make a team you can ask people to rate it so they'll let you know how noobish you are. Good for learning everything about pokemon.