Optimus Prime

Entrance
Optimus drives onto the battlefield in his truck transformation, then transforms into his robot mode.

Neutral B: Ion Blaster
Optimus Prime fires a shot from his ion blaster, causing some moderate damage and a small explosion. If the move is charged for four seconds, Prime can fire a more powerful shot that will cause a bigger explosion. In addition, pointing the gun downwards can give Prime a small upwards boost, allowing for a vertical recovery.

Side B: Trailer Truck Transformation
Optimus transforms into his trailer truck alt mode. While in his trailer truck mode, Prime can shoot some lasers by pressing A, and stops until he hits an opponent or reaches the ledge of a stage. The player can move with the control stick, and can revert back to robot mode by pressing B at any point. However, doing so will also cause the trailer to transform into a temporary base where Prime can fire a stationary machine gun hooked onto it. The trailer stays in this form for five seconds, then disappears.

Up B: Rocket Pack
Optimus Prime flies upward through a rocket pack on his back. You can charge the move for as long as you want, and use the control stick to determine the direction where Prime launches after initiation. Launching speed depends on how long you hold B for, with the maximum time being five seconds.

Down B: The Autobot Run
Optimus summons one of three Autobots to briefly aid him in battle, all three follow him around the battlefield:

Ironhide (default choice) shoots his hydro pump downwards, freezing a section of the floor. Opponents caught in this area either by standing or walking into that position during the attack will be unable to move for two seconds  afterwards, but they can get set free by other opponents. The frozen liquid stays on the ground for four seconds after it the attack is done.

Wheeljack (tilt up after Down B) uses a remote control to briefly stun a nearby opponent, and place him/her under Wheeljack's control for the time he is out. It can be undone by knocking out Wheeljack, and the move won't work unless there are some opponents in front of him.

Roller (tilt down) has the shortest spawn time of the group (8 seconds), but is also the fastest attacker. Once he is summoned, pressing B makes Roller dash at an opponent, dealing damage to them.

The Autobots stay with Optimus for as long as 13 seconds before they disappear, after that, Prime must wait for two seconds before calling another one. Alternatively they could get knocked out by an opponent with enough attacks dealt to them, ending their support early.

Final Smash: Lighting Our Darkest Hour
Optimus Prime holds up the Matrix of Leadership, and says for it to “light our darkest hour”. When the Matrix is released, it creates beams of light surrounding it, causing electrical damage to opponents in its way. These beams move in a circle surrounding Prime for 10 seconds. If an opponent dodges the beams with good timing, they can hit Prime and end the FS early. The move can also be initiated in midair.

KO Sounds
KO Sound 1: "Oh no."

KO Sound 2: *screams*

Star KO: "MEGATROOOON!"

Taunts
Up: "Amazing. A booby trap that actually captures boobies."

Side: "Autobots, transform and roll out!"

Down: "Is this some kind of game?"

Victory Options
Option 1: "I thought you were made of sterner stuff."

Option 2: "No point of chasing after them. Here's the trophy I want."

Option 3: Prime says "All right, let's go home!", then transforms into his truck mode and drives away.

Option 4 (only against Galvatron): "You're old, Megatron! Yesterday's model, ready for the scrap heap!"

Lose Pose: Prime appears wounded and lying down, with his chest opened to reveal the Matrix of Leadership.