Mega Evolution:  New Ability:
New Ability: Full Mecha Body
Ability Description: Full Mecha Body prevents any stats from being lowered what so ever.
No Mold Breaker
No Neutralizing Gas
No Haze or Clear Smog
Not even its own Close Combat
Reasoning:
First, unfortunately Brass Bond kind of sucks and is hard to balance. It’s either getting +3 from Trailblaze in 1 turn + over 60% chance to flinch Iron Heads on a sweeper or glorified x1.2 boost to your attacks that also cause you to take more damage from Rough Skin and Rocky Helmet.
It also kind of goes against Mega Falink’s own design thematically. All the little guys form a new 1 guy like Power Rangers or Voltron. So if anything, Brass Bond should COMBINE moves in some way.
Second, this new ability is derived from and is an upgrade to Full Metal Body, which itself is derived from and is an upgrade of Clear Body.
The idea is that Falinks is an all in type of Pokemon mechanically. Its signature move giving an Omniboost in exchange for not being able to switch out highlights that trait. Once you use it, there is no turning back.
The purpose of Full Mecha Body would be to ensure Falinks can’t be screwed over in any way by Intimidate, Parting Shot, Memento, or its own Close Combat.
Preventing your own Close Combats from dropping your Defenses being a huge deal. After all, using Close Combat once effectively makes No Retreat a single Dragon Dance, and using another fighting move makes you significantly weaker.
It also thematically makes sense too. It’s literally a reference to Mecha TV series. It also creates a FULL BODY too.
Third, in issues with balancing, Mega Falinks has enough flaws to where you still need to soften up your opponent’s team and position correctly to pull off a sweep.
You still do nothing against Unaware Clefable as Unaware would still ignore your stat boosts, it just never decreases them.
Falinks before Mega Evolution has to be cautious around Sticky Webs since it would lower your speed and you’d end up with 0 speed boosts on a Pokemon with only 100 Speed.
Mega Falinks is still vulnerable on the special side and can go down to strong Fairy or Psychic attacks.
Mega Falinks is also still vulnarable to burns, which means burning it after it uses No Retreat makes it a sitting duck you can take advantage of.
Mega Charizard X also exist and is actually similar to Mega Falinks statwise. Similar physical bulk too.
252+ Atk Guts Conkeldurr Close Combat vs. 0 HP / 0 Def Falinks-Mega: 262-310 (96.6 - 114.3%) -- 81.3% chance to OHKO
252+ Atk Guts Conkeldurr Close Combat vs. 0 HP / 0 Def Charizard-Mega-X: 312-367 (105 - 123.5%) -- guaranteed OHKO
The biggest difference coming in Special Bulk which Falinks obviously worse, as well as Special Attack which neither are gonna use.
Both have their own advantages and disadvantages in other regards from boosting moves to attacks and of course abilities with Mega Charziard getting Tough Claws.
This is to say that if the Meta is more than prepared for Mega Charizard without No Retreat, it can definitely handle Mega Falinks with no drawback Close Combats and not cucking its 1 time Omniboost.
Also kind of puts into perspective how Brass Bond makes Mega Falinks just a worse Mega Charizard. Losing 7/8ths of your HP to a Rocky Helmet Garchomp on all your moves, having higher chances of procing Static or Flame Body, and doing less damage because of damage rolls.