OK so first off a little background on me. I'm windsong and was actually pretty good at this game at one point. I got nominated (and in 2012 won) for Smogon's best RU player 2011 and 2012 I was also a tutor at smogon for their battling101 program for a while specializing in BW OU and I've got a couple decent tour tops and **** here and there and have voted in around a dozen suspect tests in various tiers from ADV to BW2 OU.
Anyways, enough of that garbage, this isn't supposed to be a giant RMT or any of that bull that nobody cares about, this is supposed to give all you beginning players a shot at being on par with the best guys out there.
Stuff That People Think Matters In Being Good
OK Let's go through all of these. The biggest one is Tutoring - B101, Serebii's former Competitive Tutor Program, etc. I can 100% guarantee that, at least for the BW2 OU metagame, almost anything a tutor could tell you regarding battling or teambuilding you could learn on your own. Competitive battling tutoring somewhere like smogon will have the benefit of getting you more involved in the community, possibly getting you some decent teams, but in terms of actually learning stuff, you can learn just as much by playing and gain more confidence in your own playing abilities if you work things out on your own.
Prediction is a ******** concept that was established heavily by bad players and good players trying to impress bad players. Far more important than prediction for any player is a long term game plan. This is why ADV is always better than any BW metagame - players might literally have to think of scenarios a hundred turns ahead. Thankfully, for those of you who want to be good at BW2, it's only a matter of visualizing possible gamestates ~5 - 10 turns ahead. Don't bother with any of this "prediction" - simply focus on establishing a gamestate where you have the highest possible chance of winning.
Originality is a great thing. However, if you're playing Mons competitively, treat it as a competitive game. If you think of some set that demolishes the metagame or want to use some team or something that wrecks common teams, go for it. I'm definitely not a hater on this topic - I personally wrecked stage 5 (iirc) BW2 OU suspect ladder completely with sunstall because nobody was ready to handle cresselia at the time. But the point is, unless you can provide a reasonable justification for using random stuff, just don't use it. It's also much better to stick with standard stuff unless you seriously know what you're doing and can analyze the metagame properly.
Stuff That Actually Matters In Being Good
- Understanding of Risk vs Reward
- Playing More
Let's start with the first two - your friends and connections. Your biggest asset in this game is the other players. Those smogon analysis that have the "standard" sets? They're not written by some faceless entity, they're written by other players just like yourself. The fact of the matter is, if you're friends with people who know what they're doing, then you have a better shot at being good yourself. Simply because these friends and connections are all resources - you can ask someone for a team, ask them to test battles with you, or even talk about what they're using, tournament trends, and just gain encouragement towards success from them. In addition, if you can be friends with guys who are seen as excellent players, people will hold you to a higher standard of play. And that increases one's confidence. And a confident player is always better than an underconfident player.
Teambuilding is another key aspect in being successful at the BW2 metagames. With games being incredibly quick (often <25 turns) and the fact that it's literally impossible to have a team that counters every BW2 threat teambuilding is one of the most important aspects of being good. I can be the greatest at setting up lategame scenarios and manage to make the correct move every single turn against an opponent, but if they have double dance landorus and I have no Lando counters, I'm gonna lose. Regardless of how well I play. Build your teams well. Test your teams against good players - not random guys in the <2000 range on the ladder, but more serious, good players.
Understanding of Risk vs Reward is probably the second most important factor in BW2 success (other than teambuilding). Every move you make is a decision of risk vs reward. You need to determine your endgame conditions that let you win and then always make the move that gives you the greatest chance of winning. If you can't win a game unless you get a specific kill or weaken something to a certain point, then take necessary risks to do so. Don't sacrifice a mon that's your only chance of breaking your opponent's defensive core. Analyze every single move and make sure that whatever move you click brings you one step closer to a winning endgame scenario.
And finally, the single most important thing that one can do to get better at this game is simply to play more. If someone plays one game a month and someone else plays 200 games a month, the person who plays 200 will better understand metagame trends, will better be able to visualize endgame scenarios more consistently, and will simply be able to understand more of an opponent's team from simple stuff like team preview.
With that being said, good luck and happy playing!