As I promised, working dungeon and floor increase/decrease codes. You can find these and many more in the massive cheat compilation located in my signature so go take a look if your interested.
PMD: Explorers of Darkness
::(R4) L+Left to 'Decrease' Dungeon
:::Only use if the non R4 code doesn't work
74000100 FF00000C
94000130 FDDF0000
DA000000 021ACADF
D4000000 0000FF00
D7000000 021ACADF
D2000000 00000000
::(R4) L+Right to 'Increase' Dungeon
:::Only use if the non R4 code doesn't work
74000100 FF00000C
94000130 FDEF0000
DA000000 021ACADF
D4000000 00000100
D7000000 021ACADF
D2000000 00000000
::(R4) L+Down to Decrease Floor in Dungeon
:::Only use if the non R4 code doesn't work
74000100 FF00000C
94000130 FD7F0000
DA000000 021ACAE0
D4000000 0000FF00
D7000000 021ACAE0
D2000000 00000000
::(R4) L+Up to Increase Floor in Dungeon
:::Only use if the non R4 code doesn't work
74000100 FF00000C
94000130 FDBF0000
DA000000 021ACAE0
D4000000 00000100
D7000000 021ACAE0
D2000000 00000000
::L+Left to 'Decrease' Dungeon
74000100 FF00000C
94000130 FDDF0000
DB000000 021ACAE0
D4000000 000000FF
D8000000 021ACAE0
D2000000 00000000
::L+Right to 'Increase' Dungeon
74000100 FF00000C
94000130 FDEF0000
DB000000 021ACAE0
D4000000 00000001
D8000000 021ACAE0
D2000000 00000000
::L+Down to Decrease Floor in Dungeon
74000100 FF00000C
94000130 FD7F0000
DB000000 021ACAE1
D4000000 000000FF
D8000000 021ACAE1
D2000000 00000000
::L+Up to Increase Floor in Dungeon
74000100 FF00000C
94000130 FDBF0000
DB000000 021ACAE1
D4000000 00000001
D8000000 021ACAE1
D2000000 00000000
PMD: Explorers of Time
::(R4) L+Left to 'Decrease' Dungeon
:::Only use if the non R4 code doesn't work
74000100 FF00000C
94000130 FDDF0000
DB000000 021ACB9F
D4000000 0000FF00
D8000000 021ACB9F
D2000000 00000000
::(R4) L+Right to 'Increase' Dungeon
:::Only use if the non R4 code doesn't work
74000100 FF00000C
94000130 FDEF0000
DB000000 021ACB9F
D4000000 00000100
D8000000 021ACB9F
D2000000 00000000
::(R4) L+Down to Decrease Floor in Dungeon
:::Only use if the non R4 code doesn't work
74000100 FF00000C
94000130 FD7F0000
DA000000 021ACBA0
D4000000 0000FF00
D7000000 021ACBA0
D2000000 00000000
::(R4) L+Up to Increase Floor in Dungeon
:::Only use if the non R4 code doesn't work
74000100 FF00000C
94000130 FDBF0000
DA000000 021ACBA0
D4000000 00000100
D7000000 021ACBA0
D2000000 00000000
::L+Left to 'Decrease' Dungeon
74000100 FF00000C
94000130 FDDF0000
DB000000 021ACBA0
D4000000 000000FF
D8000000 021ACBA0
D2000000 00000000
::L+Right to 'Increase' Dungeon
74000100 FF00000C
94000130 FDEF0000
DB000000 021ACBA0
D4000000 00000001
D8000000 021ACBA0
D2000000 00000000
::L+Down to Decrease Floor in Dungeon
74000100 FF00000C
94000130 FD7F0000
DB000000 021ACBA1
D4000000 000000FF
D8000000 021ACBA1
D2000000 00000000
::L+Up to Increase Floor in Dungeon
74000100 FF00000C
94000130 FDBF0000
DB000000 021ACBA1
D4000000 00000001
D8000000 021ACBA1
D2000000 00000000