While we’re at it.
Ability: Dauntless Shield
Still asking for Mega Chesnaught to get Dauntless Shield. The DLC introduced a ton of new threats and some competition. Such as Mega Golisopod, which gets a very similar stat distribution (idk why GameFreak keeps making Megas with similar stats), but also has Regenerator. Even without Regenerator, Golisopod has a vastly superior defensive typing, higher Atk, and access to moves like U-turn.
With Dauntless Shield, that 172 Def increases to extreme heights. Letting you both tank physical hits even better, and fire off powerful Body Presses even without investment.
252+ Atk Baxcalibur Icicle Spear (5 hits) vs. +1 252 HP / 0 Def Chesnaught-Mega: 210-250 (55.2 - 65.7%) -- guaranteed 2HKO after Stealth Rock
252+ Atk Baxcalibur Icicle Spear (5 hits) vs. 252 HP / 0 Def Chesnaught-Mega: 310-370 (81.5 - 97.3%) -- approx. 1.6% chance to OHKO after Stealth Rock
0 Def Chesnaught-Mega Body Press vs. 0 HP / 0 Def Baxcalibur: 300-354 (80.8 - 95.4%) -- guaranteed 2HKO
+1 0 Def Chesnaught-Mega Body Press vs. 0 HP / 0 Def Baxcalibur: 446-528 (120.2 - 142.3%) -- guaranteed OHKO
It’s a pretty stark difference in bulk and power.
And Bulletproof is nice, it doesn’t benefit from it that much. Mega Lucario Z can use Flash Cannon, Gengar can use Sludge Wave, and Gholdengo can Make It Rain or run Hex. It’s a minor inconvience for most Pokemon and only hinders Darkrai running Sludge Bomb over Ice Beam.
Ability: Scrappy or As One (Glastrier)
Mega Falinks even before the DLC was not very good. It was effectively a worse version of Mega Charizard X. Brass Bond making Rocky Helmet/Rough Skin deal tons of recoil damage to it, No Retreat being a 1 time Dragon Dance, having only 1 STAB, no Roost, etc. It needs more to make itself stand out, and Dauntless Shield only helps a bit.
Now with the DLC, there are a few more intimidate Pokemon, Dondozo, a lot more Status moves.
Unfortunately, Run Away doesn't let Falinks switch out after No Retreat, which majorly sucks since you otherwise could have a psuedo Shed Shell so that Falinks can set up No Retreat and escape to fight another day early on, or escape after being intimidated multiple times.
And with no custom abilities, it's kind of hard on Mega Falinks since you can't invent a new ability to solve all its issues.
Scrappy is probably the best option that fits Falinks and at least solves some of the issues it has. Being that your opponent can just switch endlessly with an intimidate Pokemon until your Falinks got -6 and you can't switch. Or even just intimidating once ruining your whole No Retreat. Additionally, Scrappy just lets Falinks spam its STAB Close Combat against Ghost types like Annihilape, Gholdengo, Mega Absol Z, Yamask-twins, etc..
Alternatively, give Mega Falinks As One. It's combining all the Falinks into 1 mecha. So it fits nicely, but also it's Moxie+. You bypass Chople Berry and As One gets protection from Mummy/Wandering Spirit.
Ability: Tinted Lens
Mega Pyroar is so ass and is in desperate need of a broken ass ability. Even with Orichalcum Pulse but for SpA, it was still pretty ass. And Mega Pyroar has only gotten worse with the DLC too. Heatran pre-Mega walls its STABs and either Mega Evolve to avoid Earth Power or using an Air Balloon. Attempting to use its Fire STAB can cause Baxcalibur to gain +1 Atk. Tons of fast Pokemon outspeed it now. Simply having Drought and there being like 1 good Sun abuser (and you know being outclassed by Mega Charizard Y) ain't cutting it any more.
Tinted Lens is just here as a "busted but not too busted ability" ability for Mega Pyroar. Was gonna give it Contrary, but we already have 2 other Contrary Megas. It doesn't fit thematically, but we have Triage Victreebel and Soul-Heart Dragonite. Plus it fits in spirit
like Guard Dog Golisopod.
Gameplay wise, this makes Mega Pyroar's life a bit easier. You get to hit everything besides Flash Fire Chandelure/Ceruledge for at least neutral with your STABs. Namely you hit Tyranitar for neutral damage with your STABs and can hit Heatran with your Normal STAB without worrying about Air Balloon or Earth Eater.
You also can hit Fire resists without worrying about x2 resists like Dondozo, Latios, Garchomp, and Gyarados. That especially helps since Mega Pyroar can break through those otherwise resists better with Fire Blast/Overheat.
252 SpA Tinted Lens Pyroar-Mega Fire Blast vs. 252 HP / 4 SpD Dondozo: 252-298 (50 - 59.1%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
252 SpA Pyroar-Mega Hyper Voice vs. 252 HP / 4 SpD Dondozo: 207-244 (41 - 48.4%) -- 10.9% chance to 2HKO after Stealth Rock and Leftovers recovery
And due to Mega Pyroar being really hazards weak, it appreciates not being forced out as often.
Personally, I'd given Pyroar "King of Pride Rock" that lets it ignore Stealth Rock and hit Rock types super effectively.