Runs of mine for those events that were done on that version have been rejected with the following message: "Gonna choose to reject runs from version 2.5.1. To me, it looks like an "incomplete" and flawed version that was quickly replaced.".

In version 2.5.1, changes were made to those events that were seemingly done on accident as they undid them in 2.5.2, and those changes made the events much faster while defeating the entire point of them. Two Trouble Kings removed the second trouble king while The Pirate Airship removed the airship, replacing it with a normal stage, so I do personally think the ban makes sense.

This forum post was made to warn other runners not to use this version, as their runs will be rejected also.