^If you've never gone into competitive battling, how did you find your way here?
My first battle in the game was in Pokémon XD. Because that one is simulated and they give you fully-evolved Pokémon, it was pretty fun, introduced basic concepts well, and gave me a better expectation than the first battles in most other games, which are basically Growl + Tackle ad nauseam. First battles are really boring in my opinion.
My first competitive experience was randomly looking up ways to play Pokémon online and finding Showdown. I tried to make my in-game team there, as noobs always do, found out that they are all in different "tiers" including Excadrill that's Uber, being intensely confused about what those 31s in the corner are for and what you're supposed to put in the EV boxes, and giving up.
After finding Smogon, I took a crack at it again, playing NU because I thought that would be easier than OU and would have more variety. It was a rain team, which was a pretty good strategy then, and used on-site sets, but it completely fell apart in practice. I had to use Ludicolo as my lead, because it was the only Pokémon that could provide the rain the team depended on, and it generally died after a turn. After Ludicolo died, the team had no good answers to big threats like Golurk, and was overall completely unprepared for the metagame at large. I have never delved into NU since, except a mediocre Trick Room team a year or so later, and was deterred from playing again for at least a few months. Oh, and I was swept by a Cottonee. Yeah. Cottonee.
EDIT: I forgot about PBR, which I did play beforehand. My team had no SR users and I didn't really predict at all. I remember a battle I had with someone who was better than me and whenever he had the type advantage I switched; he tried to switch after me, but I was so persistent he stopped out of irritation and boredom. I think I won maybe a quarter of my matches? It makes sense, I guess, because PBR battles are 25% scrubs and 75% completely, utterly broken. :D