Is it illegal to link/host PSP flash files? Or the 6.60.PBP? I'm just wondering as I plan to update my Adrenaline black theme.
Yes, it is copyright infringement. In practice, if you do it, the most likely outcome is that after a few months or years, you'll get a cease and desist and be asked nicely but firmly to take the file down.
But the proper advice here is probably: do not offer these files for download.
Note that I'm not a lawyer and this is not legal advice.