I was definitely joking lol. I don't think I've made a serious comment this entire thread outside of ruling all if your name is Chris Fulop or Levi. I mean HONESTLY that just has to make you infinitely cooler than everyone else. Another way to be a GREAT trainer is to spam up the boards and get yourself banned horribly like my friend Ray. While I will admit I do not condone what he did, I will also admit I found it HILARIOUS. He got what he deserved though. Anyways, heres a few serious answers to how to be a good trainer. I'll go by the definition that this means how to succeed at the game and win. Thats the only real definable answer.
1.) Play to the best of your ability. Learn from your mistakes, dedicate yourself and keep playing. You WILL get better, and usually it happens in peaks. You'll hit a certain point, things start to dawn on you, and you'll progress slowly, than step up a notch. Some advance faster than others.
2.) Follow the net. You'd be surprised how much good reading good decks and strategies does. Recognise the top decks, realize what makes them win, and you'll understand winning concepts better and eventually be able to design your own and succeed easily. This is a surefire way to get better. I suggest those struggling with deck ideas go and copy a proven" Net Deck" as some call it. Sure, it takes away from creativity, but it works and wins. Not only does this help prevent you from feeling unsuccessful, but it helps in that your given a strong weapon with which to familarize yourself with what works and what doesn't. By using good decks you realize what makes it strong, and what other top decks use, and you can soon end up weeding through your own ideas and test them out while keeping them strong. It helps familarize you with draw engines, the right Pokemon ratios, how much energy is needed, and to focus decks. It also shows off how strong combos can be, but how they need to be reasonable and not overly complex. Sure, its using others work to jump start yourself, but you learn alot by experiencing success too as well as losses. Another key is that if you play and get creamed every game, what do you really learn? Give yourself good games, wins, or close losses, and you learn why you lost and why you won much quicker than if you have been murdered 6 prizes to zero every game.
As for STAYING a good trainer, you just have to stay updated with the formats. Follow what decks are getting hyped and make sure your prepared for them. Know how your deck matches up with them and what strategies give you the best shot at beating them. Know that if something happens, you lose. Know the match ups the best you can. Knowledge IS power, and while thats corny as heck, it applies a TON. I've seen strong players play 0 games for 6 months, but follow the net, and come back and win major events. Once you've became a good trainer, you've achieved the mindset required to win and its entirely up to how aware you are of the format your playing in.