Welcome to Gaia! ::

I'm a master, I can defeat any opponent, I have almost a full box of self-trained level 100 pokemon and i'm prepared for any style tournament out there!

I believe in your first post you meant conceited. Also you have a point as in the games it is possible to obtain the legendary pokemon whereas in the anime it seems impossible. No one can be a master as if they battle online with another person that has the same level pokemon as them it really doesn't make a difference. Those that brag and say that they are a master or trying to show off when they lack strategies. Its impossible to win one hundred percent of the time.

You're a master when you beat the Elite 4... (plus Gary. I mean, whatever they changed his name to now.)

However that doesn't mean you can beat other masters yet, because in all honesty it's easy to beat the Elite 4 (in the newer games).

I don't believe that being a master at pokemon is a bad thing......but by master I assume you mean someone who is merely good at battle. I also believe that having confindence in ones self is not a bad thing either. Showing confindence shows high self esteem which is generally a good thing depending on how far they go with that confindence. Like the one person Captian Hikaru T. said that he could defeat any opponent.....which in all cases he is right he CAN but that doesn't mean he WILL.....Working with your pokemon overtime gradually gives you skills which allows you defeat more opponents. Just because master hasn't been "Defined" does not mean that we have a right to judge people because they are confident. Narcisists are a whole other matter but I won't get on that topic. I believe I am a good trainer who is willing to take a challenge but I have been defeated plenty of times just like many others. You also need to remember that the anime is for viewers enjoyment while the game is for a players enjoyment which is why they give you opportunities to catch the legendary. It's a franchise method. So all in all by judging people and calling them concieted or idiotic just because they have confidence is not a very positive way to handle things. And also assuming that you know if they elaborated or not on being a master isn't fair. Your not God nor a mind reader so let's not assume. And there you have it.

You are taking this WAY too seriously.

That's why Masters build their teams to be balanced and don't need to change them from one match to another because they're designed to handle any situation.
Having all of the pokemon in the game filled and having beaten all the trainers is really just the meat and potatoes in building strong teams for cmpetetive play.