#4 Break any records
Many records have become synonymous with the Royal Rumble. The most remarkable ones being: Most eliminations in a match, longest-lasting Superstar in a match, most wins and many more. In addition to these, there are many other negative records at the Royal Rumble too, such as the least time spent a match, most losses, etc.
While WWE would not want to associate Lesnar with any of the negative records so that he doesn't become a laughing stock, the creative team must think twice before allowing Lesnar to break any records. Roman Reigns, in 2014, broke Kane's long-standing record of most eliminations in a match after 13 years.
Two other milestones that Lesnar may accomplish simultaneously are being the second Superstar to win the Royal Rumble from the first position (Shawn Michaels being the only one to do so) and lasting longer than Rey Mysterio did in 2004 (62 minutes). Both of these, along with many other memories hold a special place in the heart of the fans and it would be for the best that WWE doesn't tarnish them.