During the mission where you are Ironhide and help Jazz at housing estate south, there is a Decepticon with a hose. You cannot hit him with melee attacks until you throw something at him. Once done, you can pick him up, or when he gets up you can use melee attacks.
Megatron is the last opponent in the Autobots storyline. He will first be in his jet form and shoot up to two rounds down at you. Evade that by using your shield. After two rounds of firing, he will land. His next attack is ramming. You cannot hit him while he is still focused on ramming. When he stops ramming and stands up in one place looking around, pick up any car and quickly throw it at him. If not done fast enough, he will return to ramming. If that happens, wait for him to stop again. If done successfully, he will now attack you. Hit him in close range combat with your melee attacks. After a couple hits, he will return to being a jet. Again after two rounds of firing he will return to the ground. In his second attack, he will use his ball and chain. Throw another car at him. If done successfully, he will attack you again. Use melee attacks on him. Once again after a couple hits he will become a jet and fire at you. Do same as before to avoid that attack. After firing at you, he will go back to the ground. His third attack is the flamethrower. Be careful because it will be tough to get cars to throw at him. When he is hit by a car you threw, he will attack again. Use melee attacks on him. For the last time he will become a jet again. Use the same strategy used earlier to avoid the attack. He will land after few hits and attack you with all the attacks he used previously. Throw cars at him every after each attack. Once done, you will fight him for the last time. Use melee to defeat him.
Unlock the following bots by performing the corresponding tasks:
BOT - HOW TO UNLOCK Generation 1 Jazz - Complete all sub-missions in both story lines. Generation 1 Megatron - Collect all the Transformer Shields in the Decepticon story line. Generation 1 Optimus Prime (cartoon model) - Collect all the Autobot Faction Symbols in the Autobot story line. Generation 1 Robo-vision Optimus Prime - Successfully complete the Autobot story line. Generation 1 Starscream - Successfully complete the Decepticon story line.