For a long time, I was a "flamethrower" kind of guy. Man... Those were days. However, up until before my DSi broke, I started becoming a "leech seed" man. I had just gotten into competitive play, and my two tanks, Gliscor and Scizor, had become the stars of my team.
A good example would be my Scizor. Now, my first Scizor was a straight out Choice Band user... Until I found out Scizor could have Technician. Some of you may know where I'm going with this. :D Anyhow, I then trained a Adamant Scizor with the moves Bullet Punch, Swords Dance, Roost, and Substitute. Use Substitue, Swords Dance, Bullet Punch, Roost, Substitute... Repeat as necessary. In competitive battling, you'll often find strategy being used more han straight out offense.
So, in other words, remember kids, the best offense is a good defense!