The boss fights were reportedly psychological. You don’t fight Bowser. Instead, you fight — twisted versions of Mario’s power-ups:
According to sources close to the royal family, Princess Peach had been acting strangely in the days leading up to her disappearance. She was seen meeting with Toad, her trusted advisor, on multiple occasions, discussing matters of state and the kingdom's future. However, the content of these meetings remains a mystery, fueling speculation about a possible conspiracy. Some believe that Peach had grown concerned about the increasing power of Bowser, the infamous King of the Koopas, and his repeated attempts to kidnap her. Others suggest that she had discovered a dark secret about the kingdom's history, one that could threaten the very fabric of their society. mario is missing peach untold tale 3
Peach adjusted her crown in the mirror, but something felt hollow. Mario had already left for Bowser’s keep — alone. Again. Luigi’s mansion stood quiet, its lights off for three days now. The boss fights were reportedly psychological