Thor flies through that giant robot worm a bunch of times before killing Soundwave.
Hulk rips the fodder apart and any poor Decepticon that gets in his way.
We don't know what Hawkeye's arrows can do yet.
Cap and Black Widow save lives.
Ironman takes on Sentinel Prime and Megatron and cuts them to ribbons with the lasers.
Shockwave's worm-bot would probably be underground until it's too late to dodge its attack. It would come up from beneath them. Anyone who can't fly/jump is vulnerable to being consumed in its toothy maw.
Starscream engages Iron Man. Iron Man has been regularly beaten by enemies bigger than him and similarly armed (Warmonger, Whiplash). He was forced to run away from human-sized robots. You can bring up lasers (which was a lame cop-out in the movie) but then Megatron could fire his pulse rifle at him, one shot of which sent Optimus flying through the air. Iron Man would be obliterated.
Meanwhile other Decepticon pins down the regular Avengers with non-stop exploding shell fire. Cpt's shield can't save them all.
I'm still thinking on how to deal with Thor.
Hulk as I said is out otherwise it's too one-sided.
Sends him flying farther back... Not sure how that's going to "obliterate" him. Meanwhile, one of his rockets will be more than sufficent to take out a Decepticon.
If it can send Optimus flying through the air and leave him motionless then it would be a lot worse for Iron Man. Probably knock him unconscious and severely damage his suit. Again Warmonger and Whiplash beat him handily and wrecked his suit with melee weapons, he really isn't that durable.
Also I'm pretty sure his suit comes with only one rocket.
I guess Thor could win, but not before everyone else gets killed.
He is tanking rockets without any visible damage, he was only knocked out of the air... Meanwhile the transformers are getting taken down by machine gun fire. Sure it's going to send him flying but I doubt it will do any lasting damage as Optimus wasn't badly damaged. Also Whiplash's prototype whips were able to effortlessly cut through metal, his whips attached to the suit would be able to do similar if not greater damage. In other words, it takes a lot to put down Iron man.
Thor didn't have many strength feats, so any of the large Deceptions could possibly just grab his ass and fly him into space while he's busy posing and speaking blusterous.
He did not make a tidal wave. He made some sort of shock-wave that was powerful enough to send 15 foot tall Frost Giants back and bring down crumbling rock and ice. This didn't have anything to do with his physical strength, it was a power of Mjolnir's.
That attack isn't doing much to the Deceptions though, (most)they're larger and heavier than Frost Giants and they're more durable than ice and crumbling rock.
They had a supporting role for the Autobots who did the real fighting. It took like 50 heavily armed humans working together to bring down just one Decepticon. The kraken-bot alone would have killed them all if Optimus didn't save them.