Moleville

Moleville-1-IamTehShark.mp4

(video credit: IamTehShark)

Moleville-2-fis0324.mp4

Initiate the Croco trampoline sequence.
After the cutscene where Croco blows up the 2nd wall, go back one room and then return to the same room you were in and wait for him (avoid Fireball and the 2 Magmus in the room).

(video credit: fis0324)

Level up:

Mario [4] - ATK

Moleville-3-IamTehShark.mp4

If you're still short on frog coins, take the lower train track path below the Star Box to find the Shy Guy
Use star to KO 10 enemies (Mallow isn't guaranteed to learn Snowy at the right time later on if you fail to do this)
If you didn't stop to get 6 extra coins in Rose Way, hit the coin chest once (most optimal to do this while you have your EXP star).

(video credit: IamTehShark)

Level up:

Mario [5] - SP

Mallow [5] - SP

Geno [7] - HP

Moleville-4-IamTehShark.mp4

Watch these videos for an idea of what an optimal minecart looks like. Includes a major section skip.

You want to collect 125 coins from the minecart minigame at a minimum.

Room 1

(video credit: IamTehShark)

perfect room 2 [2965237643].mp4

Room 2

Video by Tokyo

Good™ room 3 [1185834696].mp4

Room 3

Video by Tokyo

Moleville-5-IamTehShark.mp4

Room 4

(video credit: IamTehShark)