Is there an updated list of secret opponents and how to get them? As well as what loot they drop? Sometimes they randomly show up but I'd love to know if there are other hidden ones around the site and what interesting things they drop.

has a guide here: [Discontinued] Complete List of Unlockable Challengers. Secret challengers are in posts one and two.

For the 2021 ones you’ll have to go here: Comprehensive Guide to Battle Opponents (v2). In the second post, look under the “Secret Opponents” header and all of the “Possessed” challengers will be grouped together. That was the series of challengers for that year.

We also have a community loot spreadsheet that is up to date. In the “Secret” tab you can find the solutions for unlocking the secret challengers as well as all of the loot they drop.

thank you so much! I thought I heard of posts and links but I couldn't locate them!