• Ruins/Peaches castle

  Bowser Jr = Frisk

Peach = Toriel

Boo = Napstablook

Mario Dummy = Training dummy

Goomba = Froggit

• Snowdin/Shiveria

Mario = Sans

Luigi = Papyrus

Iggy Koopa = Doggo

Larry/Wendy Dogamy/Dogaressa

Roy = Original fight.

Lemmy = Lesser Dog

Morton = Greater Dog

Wario = Grillby

Toad = QC

Ludwig Von Koopa (Party member, but in the same way you have party members in Undertale Yellow)

• Waterfall/Lake Kingdom.

Yoshi = Undyne

Yoshi-kid = Monster-Kid

Toadsworth = Gerson

Pennington = Temmie

• Hotand/Layer-cake dessert

E-Gadd = Alphys

Waluigi = Mettaton

Donkey-Kong = Muffet

Big Yoshi = So-sorry

(Core is the Lava area)

• Last Corridor/Koopa Castle

Bowser =Asgore

Talking Flower = Flowey

Koopa-Kid = Asriel Dreemurr

• Genocide Bosses

True Yoshi = Undyne The Undying

Ludwig Von Koopa = Original Boss

E-Gadd Neo = Original Boss

Mario = Sans.

Hatred Koopa-kid = Chara.