My old style of Pokemon was oddly terrible. It works very well when playing the game itself, but venturing into the vast world of online play, it would get me annihilated. During a battle with Kybyrian in Pokemon Online, I tried using my old tactics, and basically got destroyed for it. It's surprising how much more there is to Pokemon than meets the eye.
The first thing I did - like many people have already stated - is to rely on my starter. I wasn't entirely guilty of this - I was obsessed with all of my Pokemon being of similar levels - but it was noticeable that I favored my starter. One good example is that I always changed my team's order whenever a trainer came into view; I didn't want to take any chances. Having played
Black a few months ago, I've broken that habit, and my Serperior is my fifth strongest Pokemon.
Prior to breaking the habit, however, I relied on Blaziken in my
Sapphire file. It got to a point where my Blaziken was level 100, and all of my other Pokemon were hovering around level 40. This greatly hurt me in the Elite Four, and most certainly against May. However, I always adored Blaziken. I was the only person I knew that had a female one. I really loved that Blaziken, and I think losing it in my
Emerald file corruption incident - I had traded my Blaziken over to
Emerald to use against the Elite Four - I began to have less dependence on my starters.
Another bad thing I did was duplicating too many of the same Pokemon. I really loved Doduos - and wanted Dodrios - so I decided to breed them constantly. What resulted was about one hundred Doduos in my PC that I never used. Once I had trouble keeping all of them due to inbox space, I had to release all of them, except for my Dodrio that I used against the Elite Four.
Tying into my Doduo fiasco - unintentional rhyme - I was prone to train Pokemon that appealed to me on an appearance level. The best example is Exploud. When I studied Exploud's stats on Pokemon Online, I was bitterly disappointed to see that a Pokemon that I had come to love wasn't ever going to be effective against anyone except for a simple AI. I had a similar situation with Ghost-type Pokemon, and am bitterly disappointed to see just how inadequate Gengar is next to so many other Pokemon.
I like to think that I've improved with this. I - like I did when I first played Pokemon - catch all of the Pokemon for my Pokedex, but I'm more careful about what Pokemon I fight with. Appearance of the Pokemon has taken a backseat for me now that I'm more analytic about a Pokemon's stats and move sets. I'm still terrible about natures, but I think that's because I haven't really taken the time to research that sort of thing.
Attack-based moves were - and still are - the only things that I taught my Pokemon. Stat-changing moves may be useful in some cases, but I think that if you use Sheer Cold, it won't matter that your enemy used Growl five times on you. This is a very bad way of thinking, but I can never get myself to go ahead and teach my Pokemon stat-changing moves. For this reason, I'm prone to using tanks like Aggron.
Honestly, Special Attack and Attack were entire concepts that went over my head when it came to differentiating between the two. As far as I can tell now - and this is due to a lack of research on the subject - Special, or regular Attack, depends on the move's type. This - alongside damage multipliers - only contribute to the many factors that still stump me to this day. I bet I could get a clear understanding of these things if I ever bothered to research it, but I highly doubt I ever will.
The use of nicknames is entirely lost on me, as well. People always have stories of how they named their Pokemon curse words, or something humorous, but I've always just used the Pokemon's normal name. Someone uses a clever reference to name their Pokemon? I use "Kabutops." I recently nicknamed a few of my Pokemon, but they weren't much. They were just names of people I know that were placed on ugly-looking Pokemon. It's not quite as humorous as the curse words that people used when they were younger.
I like to think that I've become a smarter Pokemon player, but upon looking at all of this, I can't help but notice that some bad habits have stayed with me. I know that my tactics are entirely capable of keeping my Pokemon in good shape against an AI, but I doubt I'd do too well against real people.