You first need to set the difficulty mode in the options before entering a difficulty specific password.

Effect	Password
Level 1-1	PHACO
Level 1-2	LUXCHIE
Level 1-3	MHOLE
Level 1-4	COASTHER
Level 1-5	CHAPTAIN
Level 1-6	CHONDOR
Level 1-7	FLORHRIE
Level 2-1	DHENCHAN
Level 2-2	TEPPOU UHO
Level 2-3	HYARI MOGLE
Level 2-4	JET MHOGLE
Level 2-5	SAMHEZAME
Level 2-6	HEMONANGLE
Level 2-7	SYLPHIHE
Level 3-1	BAKUDHAN
Level 3-2	BEROCHANDY
Level 3-3	BHARBARA
Level 3-4	HO GUCCI
Level 3-5	TOTHEMOGLE
Level 3-6	HA LA MODE
Level 3-7	SWEETIHE
Level 4-1	CHULIPH
Level 4-2	HICEMAN
Level 4-3	PHENGINSAN
Level 4-4	HEDUSAHEAD
Level 4-5	CHAMELEHON
Level 4-6	THRIDENT