Ok then I will put my answer in more detail
Weakness to ground: well you already have one counter in gyrados! I would recommend ditching the life orb for it's mega stone instead. Chances are the opponent won't use a fighting type move (Because of it's flying type and won't use fairy because of no real type advantages) . So you will get a D-Dance up so time to sweep might I recommend this set:
Gyarados
Item: Gyaradosite
Ability: Intimidate (your going mega anyway so you might as well get an atack drop on your opponent)
Evs: Atk -252/ Spe -252/ Hp -6
Nature: Admant (+Atk -SpA) or Jolly (+Spe -SpA) you should already out-speed most with one or two Dragon dances
Moves:
-Dragon dance (Obviously you need this to sweep)
-Iron Head (Deal with fairies but don't attempt to beat a Mega-Mawile or Klefki)
-Waterfall/ Aqua tail (You said you had a weakness to ground right?)
-Outrage (Trust me after 2 Dragon dances a Lucario would have trouble with this)
Sorry i was using a bad computer and every time i made a mistake it would delete everything :-(
Or try this but I won't cover this in detail:
She's Scrafty (Scrafty) (F) @ Lum Berry
Ability: Moxie
Shiny: Yes
EVs: 156 Atk / 44 Def / 116 SpD / 192 Spe
Adamant Nature
- Dragon Dance
- Ice Punch
- Knock Off
- Drain Punch
This has sweeped an OU team 6-0 for me and after 2 dragon dances plus some moxie boosts type advantages won't even matter