Time to throw my hat into the ring.

Pokémon Name: Garbodor-Mega
Mega Stone Name: Garbodite
Stats: 80 HP / 125 ATK (+30) / 100 DEF (+18) / 50 SPA (-10) / 100 SPD (+18) / 119 SPE (+44) (BST: 574)
Typing:
Ability: Merciless
New Moves: Poison Jab, Earthquake, Throat Chop
Competitive Description: Garbodor has a massive lack of good physical moves, so the new moves help fill that void, with Poison Jab being a more accurate alternative to Gunk Shot, Earthquake giving better options against Steel types like Aegislash, & Throat Chop allowing it to fight Psychic types without being forced to carry one of its weak Dark type moves (looking at you, Payback.) Merciless is very good with poison spreaders like Salazzle or just a bonus for using Toxic. This can take hits & give them too.
Edit: Just wanted to make sure that doing this sort of thing was OK first, here are the others

Pokémon Name: Duraludon-Mega
Mega Stone Name: Duralite
Stats: 70 HP / 125 ATK (+30) / 115 DEF / 130 SPA (+10) / 100 SPD (+50) / 95 SPE (+10) (BST: 635)
Typing:
Ability: Power Grid (Steelworker for Electric moves)
New Moves: Nasty Plot, Thunder Punch
Competitive Description: Base form Duraludoin has high SpAtk, but has Swords Dance with a myriad of physical moves to use. This mega aims to be a mixed setup sweeper with the addition of Nasty Plot for special setup & Thunder Punch for use with a physical set. Also, patched up the horrendous SpDef of the base form so it doesn’t just flop over after one special move.

Pokémon Name: Coalossal-Mega
Mega Stone Name: Coalossite
Stats: 110 HP / 90 ATK (+10) / 130 DEF (+10) / 90 SPA (+10) / 130 SPD (+40) / 60 SPE (+30) (BST: 610)
Typing:
Ability: Solid Rock
New Moves: Power Gem, Energy Ball, Leaf Blade
Competitive Description: Solid rock helps patch the 4x weakness to Water & Ground, with added bulk to help further alleviate the problem. The moves added allow Mega Coalossal to run either a physical or special set, with Power Gem giving STAB & the others helping with Water & Ground types.