Ahiru's Wonderland is apparently an infamous site that hoards event Pokemon from Japan, back in Gen 3 days.
Relevant screenshots of the page will match the relevant save data uploaded.
Jan 1, 2019 edit: @shadowofdarkness shared some files he downloaded, probably back in 2007.
Interestingly, it went beyond Gen 3, and contained various Gen 4 files.
Do note that:
1. .stk files are a bulk batch of files used with pokestock
2. There appears to be some files being marked (with Pokerus) in the saves, use at your own risk.