Oh god, i'm so in with this.
If I had to come with a moveset, would be something like this.
Cloud like heavy. Between medium and fast faller. Average jump and nice grab range. Pit like run speed. Good air movility.
Normals and Smash attacks
Jab: Two punches folowed by a hammer down hit with his fists. Can kill at quite high percents (like robin fire jab)
Forward tilt: A kick similar to ganon f tilt, weaker but faster and doesn't send foes that horizontaly. Still good damage and knockback. Can kill at high percentages.
Up tilt: A headbutt. Not so great range but grants intangibility on the head and upper body. Can kill at high percentages.
Down tilt: a quick stomp in front of him. Doesn't have a good range but a good combo starter, send enemies upwards. it consist of two hits, the foot going down and the slam. Someway safe-ish on shield due to pushback and good shield damage.
Smash attacks: They use the chainsaw. Up does an arc over him, forward is a slice and down like up but on the ground, with more range. They are reasonably fast and deal a ****ton of damage and knockback, but have lot of endlag and are completely unsafe on shield.
Air attacks
Neutral air: A pistol shot. Doesn't travel very far but can be charged. Can be shot very fast up to 3 times without landing and has very low knock back. The charged shot deals more damage, has more knockback and can be shot even after landing. Almost lagless. Poor shield damage.
Down air. Shoots the shotgun with the grenade launcher mod. If it hits close to him (can happen on the ground too), propels him slighly upwards and spikes the opponent. Like megaman down air, it travels some distance before desapearing. Only explodes on contact with an enemy or a surface (or any kind of hitbox). Deals fire damage.
forward air: Shoots a 6 rocket salvo with the rocket launcher modded assault rifle. Can be tilted up and down. Very low knockback but decent damage (fire damage) and hitstun. Can be used 4 times before it enters a short cooldown. While on CD, he hits with the rifle instead. Autocancels on landing after a shorthop.
up air: 2 hits attack with the gauss cannon. Like shulk's up air, first hit he pull the cannon out, hit that connects wit the shot. Good damage but difficult to use. The hit and shot goes diagonaly towards you are watching, but can be reversed. Pushes you down when using it. It autocancels during the first hit, laggy othewise.
Back air: A punch like lucario or falcon B air. High knockback.
Specials
Neutral - Rocket launcher: If tapped, can be used instantly, shooting horizontaly. You can run while readying the shot (It is fast anyway). If you hold the button, you stay in position but you can aim 360 degrees. Can be used in the air once and can be used for a rocket jump.
Side - Plasma gun: Shoots the plasma gun. each use shoots 5 projectiles in quick sucession, can be used 3 times. After that, it transforms into the plasma pulse. deals very good damage, has nice hitstun but poor range. The ability enters on cooldown after its use completely for a short period of time. Can be used in movement.
Up - Thrust boots: A 3rd, long jump. Does not cause freefall and you can do whatever you want during it. Can only be used once without landing but refreshes after being hit, like every othe recovery.
Down - Grenade: readies a grenade (like link or snake). It explode quicker tho.
Throws
Every throw uses the supershotgun. The pummel is a punch in the face.
Up: He launches his foe in the air and shot him once afterwards. Can kill at extremely high percents.
Forward: holds his enemy and shoot him twice. Good damage but no followups and doesn't kill.
Back: Similar to F throw.
Down: Slams the enemy on the ground and shoot him twice. Combo throw at low and mid percents.
And as some other pointed before I love the idea of throws instakilling dazed enemies over x percent. Would be great.
Final Smash
Obviusly the BFG. A slow projectile that oneshots. it also deals damage to the enemies nearby.