If you're new to the game, i recommend you just playing through the game
Natures and such mean nothing as you can change them fairly easily later in the game with mints.
The game is more fun if you build your team by exploring the map. Unlike any other main series game, literally everything in the pokedex is in the game, so there's nothing you need to trade for or anything.
Feel free to send me a PM if you got any questions though
