Yep without Sam around, in the movie universe, the xmas tree also known as Megatron and Barricade would win all the way, and then randomly trip over a pair of daisies, killing themselves because the sponsors wanted it that way..
In old comic rules, Barricade wouldn't be there, and Bumblebee would be smaller and not much help to Prime.
And THAT Megatron has the Fusion Cannon, is nearly impervious, (to TF attacks, let alone puny Humans) and intelligent and malevolent as he is insane.
In the old Cartoon, again Barricade wouldn't be there, Bumblebee would now be the size of Spike nearly, and Prime'd beat Megatron, and just let him go fly off, swearing revenge, to fight another day a stupid amount of times.