For your listening pleasure:
Gimmick: Dr. Eggman fights while in his trusty Eggmobile. The design of the Eggmobile is taken after Sonic Battle, where it is more compact, has the same color scheme as Eggman himself (making alternate colors easier to make), and has two cannons loaded at the base to work for part of the moveset. He is given multiple jumps and an ability to float like Peach in exchange for an Up Special recovery.
ALSO, he cannot be grabbed by normal grabs. He can still be grabbed by special moves like the Falcon Dive and Flying Slam. And he can be Inhaled by Kirby and DDD.
Neutral Combo: Shoots a small missile out of the left cannon, then the right. Keeps going for how many times the player presses the button. Yes, this has insane range, but the missiles lack decent knockback and strength.
Forward Tilt: A boxing glove on a spring pops out in front of the Eggmobile, similar to the Egg Walker’s close range attack in Sonic Adventure 2.
Dash Attack: A drill pops out in front of the Eggmobile, similar to the first Drill Car in Sonic 2, while Eggman charges forward.
Up Tilt: Eggman swats above with his arm.
Down Tilt: An electrical prod pops out in front of the Eggmobile near the bottom.
Forward Smash: A giant hammer pops out in front of the Eggmobile and it slams down in front of it.
Up Smash: Two drill arms pop out at the sides of the Eggmobile, and propel upwards, drilling opponents.
Down Smash: Two circular saws form at the sides of the Eggmobile near the bottom and spin around the machine, hitting both sides.
Neutral Air: Electric field (similar to Mewtwo)
Forward Air: Flamethrower burst with the two cannons.
Back Air: A mechanical boot pops out of the back of the Eggmobile and kicks.
Up Air: Eggman shows a display of fighting capability and strength by punching upwards twice.
Down Air: A spike pops out at the bottom of the Eggmobile, and Eggman falls, attempting to prick opponent below.
Grab: Two smaller versions of the arms from Big Arm from Sonic 3 form on the sides of the Eggmobile, and he grabs with the hands.
Pummel: He crushes the opponent in the hands.
Forward Throw: Overhead flings the opponent forward.
Up Throw: Flings the opponent upward.
Back Throw: Turns and lets go the opponent, flinging them.
Down Throw: Rises, then slams the opponent down, and lets go.
Neutral Special: Egg Bombs-Eggman tosses three bombs forward at a downward arch, each being a pace apart from the last. (Taken from Sonic the Fighters)
Forward Special: Bumper Arms-Two Bumper Arms pop out the sides of the Eggmobile, and propel forward, one arm at a time. This pushes opponents back, and reflects projectiles. This is similar to Sonic CD’s first boss.
Up Special: Missile Launcher-A missile launcher pops out of the back of the Eggmobile, and strong missiles are launched to the sky and fly towards opponents. (Taken from Sonic Adventure 2)
Down Special: Wrecking Ball-Eggman flies up a few paces (if in the air, he doesn’t) then drops down a miniature wrecking ball from the bottom of the Eggmobile. For a few seconds, he can hover in place and move back and forth, which swings the wrecking ball. When the attack is over, he goes into helpless state.
Final Smash: Death Egg Robot-Eggman flies up off the screen and comes crashing down in the Death Egg Robot. Whichever way Eggman was facing will be the way the DER will be facing, and it can’t turn around. In it, he is able to walk around to run into opponents and shoot the arms of the robot forward. He can also jump. HIGH.
So, what do you think? Decent? Needs work? Give me constructive criticism, please.
EDIT: "How would he use items?" is a question that I'm surprised it wasn't asked. Anyways, to use items, a robot claw like one of the ones from his Sonic the Fighters mech pops out of the side of the Eggmobile to hold on to items and use weapons.