I believe the only time the Decepticons have ever been consistantly victorious over several episodes was during the latter half of Armada's first season.

 

because the humans have to win and beat up at least one of the evil whatevers so everyuone has a good feeling

 

Yes, because Starscream might be a good warrior, but not really a good leader.
Starscream was a powerful character who caused hard times for Ratchet and Ironhide and crushed many F-22As.
Blackout is like Soundwave, a silent loyal soldier under Megatron.
Brawl was actually very tough and was only defeated after Jazz, Ratchet, Ironhide, Bumblebee and the soldiers attacked him until his armor was finally breached. Bonecrusher was maybe too selfconfident to fight Optimus Prime 1on1.
Barricade was defeated once by Bumblebee but we don't know what happened to him after the highway chase.

 

I was pretty annoyed at the human resistance to the Decepticons in the movie. No friggin' way the US Army would have given the 'Cons that much of a fight. Especially when Blackout dispatched the US Base with ease. Why didn't he use that powerful weapon we saw at the stomping of the Quatar Air Base in the final battle??? Human takes him out with one well placed shot after he's hit by a couple missles? I don't think so!

 

Well its something that did with those shows. I mean they think having the villians win would hurt a kids "morale" or somethin.

That annoyed too! I mean come on be consistent! If his EMP can disrupt what they're doing and he has his blades then why don't you have him use it in battle most of the time?

 

Think about it. The Autobot's had the Allspark with them in the Final Battle. If the 'Cons used the big weapons like Blackout did in Qatar, they would have risked damaging or possibly even destroying it.

 

The Autobots would have wiped them out if they were evil.