Offensive (Mega) Scizor, Bisharp, Fairy types who happen to be faster than Dragalge and being able to threaten it like Mega Altaria, Mega Diancie and Mega Gardevoir give the team some troubles, especially for Mega Absol, Lantherian as a glue alone isn't enough that's why I would like to nominate a revengekiller that can help against said threats.
Choice Scarf Heatran
Heatran (M) @ Choice Scarf
Trait: Flash Fire
EVs: 20 Atk / 236 SAtk / 252 Spd
Naive Nature (+Spd, -SDef)
- Earth Power
- Fire Blast
- Stone Edge
- Flash Cannon
Naive allows Heatran to outspeed 108 Mega Charizard X after a Dragon Dance, the usual bulky variant, Stone Edge with 20 atk evs will allow Heatran to always ohko 252 HP Talonflame, while Flash Cannon and Fire Blast acts as STABs.
Heatran can come in as a check against Mega Gardevoir, Mega Diancie and Mega Altaria and threaten them with Flash Cannon, while also being able to stop a +1 Defiant Bisharp (Black Glasses adamant +1 Sucker Punch will always fail to ohko Heatran, even with Stealth Rocks in the field) and Offensive mega Scizor from rampaging the team.
Of course, due to Heatran's solid type the team also gets a solid ice, dragon and fairy switch in.