I used to crazy into it but I quit a little after ORAS came out because I wasn't a fan of how the metagame changed. But it was really fun for a while and I even managed to make it to the top 30 on the UU ladder. Honestly I just used pokemonshowdown.com because don't have to go through the trouble of breeding or ev training. Also I had a bunch of friends I made on there. If you wanna get into competitive then i'd just use pokemon showdown because its easy to get practice in and try out new teams really efficiently, but you'll suck at first trust me.
I have been a fan of the series for years and have never once battled another person competitively. I dropped off when Gen III hit and returned to the series with HeartGold and SoulSilver. When I learned about IVs and that people could get 5 or 6 perfect when I could only get one if I'm lucky? Ha, nope.
Since then, because of the new breeding mechanics introduced in Gen VI that make IV breeding more accessible, I have been breeding 5 IV Pokemon. I'm going to have my first battle against a friend after I beat the Elite 4 in Alpha Sapphire. Whether that will be a stepping stone toward joining the competitive scene is yet to be seen.
I breed competitive Pok?mon because its fun to me, I know it sounds so boring, but I guess the satisfaction of successfully getting a "perfect" Pok?mon is the fun in it. Kind of like doing the tedious tasks in AC tbh. But, I never actually get to use them now lol, I know too little competitive people and I also don't really like how inconsistent Smogon's rules are...like why are some non mega's allowed to go to the lower tiers and then others are stuck onto their mega and also why are some mons like Gothitelle allowed in the lowers tiers with her lessor abilities, but Blaziken is stuck in ubers? I get that shadow tag is the banned thing and not the Pok?mon, but still. So I guess I casually play competitive games with friends, using smogon rules that make perfect sense like sleep clause and so on.
I did it when I had pokemon Y. I went crazy trying to breed the perfect IVs. I got tired of people using the same pokemon over and over (greninja, ferrothorn, talonflame, garchomp, azumarill, and blaziken) and people who thought legendaries were an end all (so your mewtwo uses ice beam on my dragonite, mega evolves on the second turn, but then uses aura sphere?). I built my team to practically counter most OU. I don't really like smogon standards either.
I sometimes play on Showdown and I made one competitive team in XY. I got lazy and did only 3 IV Pokemon or 4 IV for stats that weren't needed. EV training was really easy and only took 10-20 minutes per Pokemon. Seems boring but I was pretty happy because I felt accomplished xD. Doing only 3 IV's didn't really matter in the long run but not putting perfect IV's into Attack on my Dragonite was definitely a mistake.
I'm afraid to dip my foot into competitive. Sometimes I just like to breed Pokemon with good Natures and use Super Training for fun. But I never get super serious with breeding, battling, and that IV+EV junk.