>>58708009If we're allowed to affect them through leveling, evs, items, and moves, then i think it might be Eternamax. If a defensive raw stat is exactly equal to 655 (in gen 8 at least), then the damage recieved from the respective category of move will overflow to only 2hp. Even if Mega Zygarde gets to +6 and uses Nihil Light, only 2hp. Only Eternamax Eternatus's defensive stats are high enough to make this possible, however it can only be achieved with a positive nature as well, so you have to choose between walling all physical moves or all special moves. Even with no defense investment, the other defensive stat is still even better than Blissey tanking a special hit while also being able to Toxic, Recover, hit really hard with it's stabs, outspeed most of the meta, and with an extra little treat of applying Pressure to the moves that hit it. Just switch bold Eternamax into any physical attacker and calm into any special attacker, and the powerful bp moves they're using will soon vanish. If you can't use damage over time on it Leech Seed, Curse, Salt Cure, or Struggle recoil, then you can't do anything really against it as I'm pretty sure the boss version is immune to OHKO moves and Destiny Bond too.