>battle him before you reach the Elite Four
>spider lillies everywhere
>"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."
Wally died and the guy you see in the post-game is his ghost, puppeteering his own corpse because his soul is doomed to walk the earth until he beats you.
