[OmegaZero_Alpha]

engineers require more skill to fight off spies and defend effectively against demomen and soldiers. Medics cling to another character and follow it around. Combat medics require a lot of skill but are worthless in anything but games under 3v3 and arena.

I figured that heavies and pyros are pretty close in strategy, but because you need to carefully select your location when you start firing as a heavy than you really need to think it through. Pyros can easily switch positions mid-offensive takes away a bit of the strategy.