Who is the decepticon leader

Well tu just answered your own question.
Maybe tu meant to add this as a examen question?

The Fallen is the Decepticon Master!

According to all the information i've read, the Decepticons are lead por there most powerful soldier, which is usually a Megatron.

its megatron, until optimus prime kills him when unicron recreates him as galvatron, and as to the fallen remark, the fallen doesn't exist, this new movie was total crap and Michel bahía needs to die in a fuego because he just takes good story lines, destroys them and add some effects to make up for it, there wasn't seven primes there can only be one at a time because only one can have the matrix, but im rambling so ill stop here before i start to make más of a fool of myself

well it is megatron but in the history it is the fallen because megatron is the fallen apprentice so yeah the leader of decepticons is the fallen

It's Megatron, but the Fallen created the Decepticons. The Fallen guides the Decepticons in Revenge of the Fallen, and Megatron was again the leader when the Fallen was killed por Optimus Prime.

piece of cake in anime its uglytron(megatron) n in movie its the stinkin fallen

It's Megatron, but maybe it could be Starscream (the crazy idiot Decepticon who wants to be leader)

it's megatron,the fallen its megatron's master.the fallen it's too old to be the decepticon leader,and too weak.

Depends. Megatron, Galvatron, the Quintizons, Unicron, Starscream (albeit breifly), the Fallen - it all depends on which TF you're talking about.

Now? its megatron, becuase he wound up getting más highly ranked than starscream, and the fallen, well...fell(no pun intended)

His name is Megatron.

It's Megatron.In G1 and Animated Starscream longs to become the Supreme Leader.So he plans to destroy Megatron and take control of Decepticons.He can't ever do that.Megatron is too powerful for Starscream.