I'm just gonna go with Bronzong because it's a bell and therefore can't technically die. Also, another definition for deathless is "likely to endure because of superior quality," and since Bronzong was said to have been dug up intact after hundreds of years, I'd say that definition applies.
I'm trying way too hard aren't I
Yay A2A is back
Burakoru - Petilil
Gryghaim - Magcargo
BlazikenBlitz - Dwebble
WandererBeta - Cascoon
CuriousHeartless - Deerling
Crimson Penguin - Bronzong