With the first four codes, if you die at a boss stage, you will get 2 mintes.

DFC9-4F82 1 minute for stage 1 instead of 4
DBC9-4F82 9 minutes for stage 1
DFC9-4472 1 minute for stage 2 instead of 4
DBC9-4472 9 minutes for stage 2
C2E9-47DE Infinite time
DF6B-1D60 + DF26-15DF Lose power more quickly
D96B-1D00 + D926-11AF Lose power more slowly
DF6C-1460 + DF2B-156F Gain power more quickly
4D6C-1400 + 4D2B-150F Gain power more slowly
DD6B-1D00 + DD26-11AF Infinite power
DBEF-1D6E 1-up with every coin after you get 10
DD67-1D50 Start with 1 life
D067-1D50 Start with 5 lives
DB67-1D50 Start with 10 lives
C228-376D Infinite lives
C221-116D + C283-4FAE Almost infinite health
C28F-3D02 Don't lose coins when you miss a jump

With the last two codes, after 30 you start with 10
F3EF-1D6E 1-up with every coin after you get 30
14EF-1D6E 1-up with every coin after you get 99