>>29468405Okay, I'm going to explain this once more so people finally get it.
When you face Wally just before the League, you battle him in a field of spider lily flowers.
>Some other legends have it that when a person sees someone that they may never meet again, these flowers, also called red spider lilies, would bloom along the path.>Perhaps because of these sorrowful legends, Japanese people often used these flowers in funerals. >...They are described in Chinese and Japanese translations of the Lotus Sutra as ominous flowers that grow in Diyu (also known as Hell), or Huángquán, and guide the dead into the next reincarnation.This is the last time you see him alive. Wally died while you defeat the League, and the guy in the post-game is his ghost, puppeteering his own corpse and keeping it fresh with some supernatural magic.
This is why he hasn't aged since ORAS.