Rooks and Kings is an EVE corporation that has published a few videos that display some great fighting skills. They demonstrate probing, and when you take a look at the equipment being used, you can see that some ships are made for electronic warfare, while others are snipers, and others are simply drone carriers or scouts.
The lesson is that for a fleet to work well, it needs to be in constant communication (which means using EVE Voice or Teamspeak or Ventrilo) and each ship must play a specific role with maybe a minor role thrown in. You'll need scouts to make sure your gigantic battleship doesn't warp into a system and get blown to bits, you'll need electronic warfare ships to disrupt enemy targeting and to protect your own ships.