Lucario

With its good offensive Fighting / Steel typing, above average base 112 Speed, access to Close Combat, and unparalleled power with Adaptability, Mega Lucario is a serious threat in the Uber tier. It also has access to Swords Dance, which pressures entry hazard removers and allows Mega Lucario to decimate stall teams by easily finding setup opportunities on stall staples such as Blissey, Clefable, Ferrothorn, Tyranitar, Lugia, and Arceus-Water without Judgment. As if Mega Lucario doesn't pose a big enough threat to stall already, it also sports a nifty immunity to Toxic and a 4x resistance to Stealth Rock, meaning that it must be dealt with directly, as merely phazing it can allow Mega Lucario to find more setup opportunities during the match. Mega Lucario is no one-trick pony, though. With access to Bullet Punch, Mega Lucario functions as a revenge killer to Geomancy Xerneas, meaning that it does have utility against balance and offensive teams, overall making it a solid offensive Pokemon across the board.

However, although Mega Lucario has a theoretically decent defensive typing with good resistances to Dark, Ice, Normal, and Dragon, its paltry 70 / 88 / 70 bulk means that it cannot switch into any attack and that it is checked by just about anything that outspeeds it and has a decently powerful coverage move. Mega Lucario also faces heavy competition from other offensive Mega Evolutions, especially Mega Salamence, which is faster, stronger, and bulkier. Although Mega Lucario has utility against offense and balance by being able to revenge kill a +2 Xerneas, it has a difficult time finding setup opportunities against offensive and balanced teams because of the offensive pressure they apply. Balance teams are especially a trouble for Mega Lucario, as they can exert a mix of offensive and defensive pressure and are able to KO it, wall it, or cripple it with status ailments. However, none of this is enough to subdue Mega Lucario's vital spirit; Mega Lucario is the rising star of the Uber tier that has a specific niche of being a soft check to Geomancy Xerneas and a stallbreaker that is very difficult to stop when boosted.