LogFAQs > #968199380

Peach actually has a significant durability advantage here if we give her Lazy Shell (which is debatable as that's a universal piece of equipment rather than Peach-exclusive but, for the sake of argument, sure let's give it to her). Having that plus Calm Vibe essentially gives her passive regeneration and a sky high defense that DK CAN pierce, but not fast enough to outpace. Adding in her spells, especially the ones causing sleep, and it should be a win for Peach.

The issue being, while DK can't take out Lazy Shell Peach, she can't take out DK, either. Neither her vibes nor her MP is an infinite resource, and while I'm sure Psycho Bomb could deal SOME damage, Lazy Shell not only reduces her attacking power, but also her speed to the point where any sort of athleticism she's shown would be nullified. Eventually, the Lazy Shell becomes a walking coffin, as DK (unlike Culex) does not need to rely on a finite source of MP to win the day. At some point, DK could just pick Peach up, throw her in water, and she'd likely drown from being unable to breathe or swim up with the heavy armor on. Or would discard it and get one-shotted by DK.

That, unfortunately, is her win condition. Peach's durability is nowhere near enough to survive DK's punch without Lazy Shell, and even given a full power crit frying pan or psycho bomb, isn't gonna be enough to fell DK on the off chance she gets off Sleepy Time into her best stuff. It isn't impossible for Peach to win... but DK wins many, many more times than he loses, and Peach has zero guaranteed paths to victory.