Go for The Jump over the chasm
Skip Machine Made Bowyer twice. You can avoid every encounter in the room by hugging walls on the conveyor belts and having crisp D-pad inputs near the axems.
(video credit: IamTehShark)
Level up (if you got a Bowser or Mallow clone):
Mario [14] - ATK
Geno [14] - ATK
Bowser [15] - HP
Level up (otherwise):
Mario [14] - ATK
Geno [14] - ATK
Level up (if you got a Bowser or Mallow clone):
Mallow [16] - SP
Peach [15] - HP
Level up (otherwise):
Bowser [15] - HP
Peach [15] - HP
If you switched Peach in during Cloaker/Domino fight:
Proceed to Inner Factory
BOWSER'S KEEP (2) | OUTER FACTORY | INNER FACTORY