Route 1

On Route 1, the professor will demonstrate catching Pokemon. She will catch a Patrat properly, unlike the tutors from past generations. You can find Patrat and Lillipup in the tall grass. I recommend catching both, for the sake of filling up your Pokedex. Lillipup is more of a damage dealer with fantastic stats. Patrat is a bit subpar for now. Patrat can be an impressive disruptor, but that's about all Patrat has. If you want either, feel free to hold on to them.

Train up the Pokemon you plan to keep until all of them are at least Level 5, preferably higher. At the end of the route, you'll run into your homies. Compare Pokemon. You get nothing for having more than them so don't worry. You will get a call from Professor Juniper, who tells you to go to the Pokemon Center. Head over there!