Zacian can tank a tera steel mega metagross Steel Roller and barely miss the OHKO back with close combat.
+1 64+ Atk Zacian-Crowned Close Combat vs. 4 HP / 0 Def Tera Steel Metagross-Mega: 298-352 (98.6 - 116.5%) -- 93.8% chance to OHKO
Against non tera steel, it can still live a steel roller, but it can't hit back as hard since it needs crunch to hit SE. Metagross actually wins this exchange with steel roller + bullet punch getting the KO unless he rolls min damage on both.
Other than broken legendaries, I think azumarill is your best bet, living heavy slam, going 50/50 against steel roller and dealing 50 back with banded superpower.
252+ Atk Tough Claws Tera Steel Metagross-Mega Heavy Slam (120 BP) vs. 252 HP / 252+ Def Azumarill: 338-398 (83.6 - 98.5%) -- guaranteed 2HKO
252+ Atk Tough Claws Tera Steel Metagross-Mega Steel Roller vs. 252 HP / 252+ Def Azumarill: 364-430 (90 - 106.4%) -- 43.8% chance to OHKO
