I almost forgot the most important codes 
Super Game Boy 1 and 2
7E0F0700 - SGB games never override your ability to access normal SGB features (Enables All Menu Options for every game that disables your ability to access color or controller option menus and sometimes screen savers.)
7E034300 - Menu sounds are half the normal pitch (This is the equivalent of accessing all menu commands while SGB enhanced music changes in game.)
7E0F0B01 - Enables enhanced colors for ever game. (Colors are black)
7E0F0C01 - Enables enhanced borders for ever game. (Border color is the first color selected out of the possible four.)
7E0C1801 - Inf Time to enter codes
7E0C66FF - Keep screen saver contrast while playing (Just activate the screen savers with L L L R and start playing. Does not work on movie set border)
7E0C66FF
7E0C16FF - Credits auto start after Boot-up
7E0FE944 - Pauses Credits for easy reading
7E02FA07 - Disables RAM saving
All of these code's descriptions have been edited for professionalism and shortness for convenience. There also more SGb codes, still.
Cool Spot (All versions)
Rapid Fire
7E1DF200
Pac-Attack
Title and Menu music modifier (Now you can listen to your favorite song in the menu)
7E002EXX
00 - No Music
01 - Normal Mode Them
02 - Normal Mode Critical (The Can Can)
03 - Menu
04 - 2-Player Game Over Theme
05 - Game Over
06 - Credits
07 - Stage Clear
08 - Puzzle Mode Theme
09 - Ending
0A - 2-Player Game Theme
0B - Main Theme (Title)
0C - SFX only
0D - Records
Super Mario Kart
Player Shrink Modifiers (Affects all modes)
Player 1
7E0192XX
7E1031XX
00 - Normal
01 - Shrunk
Player 2
7E0194XX
7E1032XX
00 - Normal
01 - Shrunk
"Choose Your Driver" Message Stop Go
7E006002
Kirby's Avalanche (U)
Unlock All special Custom Mode Options
7E019401
Kirby's Ghost Trap (E)
Unlock All special Custom Mode Options
7E019401
Kirby's Dream Course/ Kirby Bowl
Kirby's Dream Course/Kirby Bowl
Course Modifier (The original course music will still play. Also Affects 2 Player Game.)
7E6A5AXX
00 - Course 1
01 - Course 2
02 - Course 3
03 - Course 4
04 - Course 5
05 - Course 6
06 - Course 7
07 - Course 8
08 - Test Course 1
09 - Test Course 2
0B - Test Course 3
0C - Test Course 4
0D - Test Course 5
0E - Test Course 6
0F - Test Course 7
10 - 2 Player Course 1 - Wispy Woods
11 - 2 Player Course 2 - Mr. Shine & Mr. Bright
12 - 2 Player Course 3 - Kracko
13 - 2 Player Course 4 - Gordo
14 - Demo Course 1
15 - Demo Course 2
16 - Demo Course 3
17 - Demo Course 4
18 - Demo Course 5
19 - Test Course 8
1A - Test Course 9
1B - Test Course 10
1C - Test Course 11
1D - Test Course 12
1E - Test Course 13
Course Hole Modifier
7E6A5EXX
00 - Hole 1
01 - Hole 2
02 - Hole 3
03 - Hole 4
04 - Hole 5
05 - Hole 6
06 - Hole 7
07 - Hole 8
Course Music Modifier (Also Affects 2 Player Game)
7E6A5CXX
00 - Course 1
01 - Course Intro
02 - Course 4 - Space Valley
06 - Course 5 - Jigsaw Plains
08 - Course 6 - Green Fields
0A - Course 8 - Castles of Cake
0D - No Music
0E - Course 9/Iceberg Ocean
1F - Menu Variant?
20 - Course 2 - Over Water
21 - Silence
22 - Course 7 - The Tricky Stuff
27 - Credits
28 - Demo
29 - Credits Variant
38 - Victory!
41 - King Dedede Battle
56 - Unknown
5B - Lose
Ability Modifier (Player 1)
7ED852XX
00 - Nothing
01 - Rock
02 - Parasol
03 - Fireball
04 - Porcupine
05 - Tornado
06 - Tire
07 - Spark
08 - High Jump
09 - Freezie
0A - UFO
0B - Possible Unused Beta Cook Freezes upon use
0C - Unknown Freezes Upon use
0D - Unknown Freezes Upon use
0E - Unknown Freezes Upon use
0F - Unknown Freezes Upon use
13 - Unknown Freezes Upon use
14 - Unknown Freezes Upon use
15 - Unknown Freezes Upon use
16 - Unknown Freezes Upon use
17 - Unknown Freezes Upon use
18 - FF Freeze Instantly
Ability Modifier (Player 2)
7ED854XX
00 - Nothing
01 - Rock
02 - Parasol
03 - Fireball
04 - Porcupine
05 - Tornado
06 - Tire
07 - Spark
08 - High Jump
09 - Freezie
0A - UFO
0B - Possible Unused Beta Cook Freezes upon use
0C - Unknown Freezes Upon use
0D - Unknown Freezes Upon use
0E - Unknown Freezes Upon use
0F - Unknown Freezes Upon use
13 - Unknown Freezes Upon use
14 - Unknown Freezes Upon use
15 - Unknown Freezes Upon use
16 - Unknown Freezes Upon use
17 - Unknown Freezes Upon use
18 - FF Freeze Instantly
More new codes
1 Player Dice Roll until you stop them
7E631E00
2 Player Dice Roll until you stop them
7E632001
Inf Lives on King Dedede Challenge (You still die if King Dedede touches Kirby)
7ED7F402

Super Game Boy 1 and 2
7E0F0700 - SGB games never override your ability to access normal SGB features (Enables All Menu Options for every game that disables your ability to access color or controller option menus and sometimes screen savers.)
7E034300 - Menu sounds are half the normal pitch (This is the equivalent of accessing all menu commands while SGB enhanced music changes in game.)
7E0F0B01 - Enables enhanced colors for ever game. (Colors are black)
7E0F0C01 - Enables enhanced borders for ever game. (Border color is the first color selected out of the possible four.)
7E0C1801 - Inf Time to enter codes
7E0C66FF - Keep screen saver contrast while playing (Just activate the screen savers with L L L R and start playing. Does not work on movie set border)
7E0C66FF
7E0C16FF - Credits auto start after Boot-up
7E0FE944 - Pauses Credits for easy reading
7E02FA07 - Disables RAM saving
All of these code's descriptions have been edited for professionalism and shortness for convenience. There also more SGb codes, still.
Cool Spot (All versions)
Rapid Fire
7E1DF200
Pac-Attack
Title and Menu music modifier (Now you can listen to your favorite song in the menu)
7E002EXX
00 - No Music
01 - Normal Mode Them
02 - Normal Mode Critical (The Can Can)
03 - Menu
04 - 2-Player Game Over Theme
05 - Game Over
06 - Credits
07 - Stage Clear
08 - Puzzle Mode Theme
09 - Ending
0A - 2-Player Game Theme
0B - Main Theme (Title)
0C - SFX only
0D - Records
Super Mario Kart
Player Shrink Modifiers (Affects all modes)
Player 1
7E0192XX
7E1031XX
00 - Normal
01 - Shrunk
Player 2
7E0194XX
7E1032XX
00 - Normal
01 - Shrunk
"Choose Your Driver" Message Stop Go
7E006002
Kirby's Avalanche (U)
Unlock All special Custom Mode Options
7E019401
Kirby's Ghost Trap (E)
Unlock All special Custom Mode Options
7E019401
Kirby's Dream Course/ Kirby Bowl
Kirby's Dream Course/Kirby Bowl
Course Modifier (The original course music will still play. Also Affects 2 Player Game.)
7E6A5AXX
00 - Course 1
01 - Course 2
02 - Course 3
03 - Course 4
04 - Course 5
05 - Course 6
06 - Course 7
07 - Course 8
08 - Test Course 1
09 - Test Course 2
0B - Test Course 3
0C - Test Course 4
0D - Test Course 5
0E - Test Course 6
0F - Test Course 7
10 - 2 Player Course 1 - Wispy Woods
11 - 2 Player Course 2 - Mr. Shine & Mr. Bright
12 - 2 Player Course 3 - Kracko
13 - 2 Player Course 4 - Gordo
14 - Demo Course 1
15 - Demo Course 2
16 - Demo Course 3
17 - Demo Course 4
18 - Demo Course 5
19 - Test Course 8
1A - Test Course 9
1B - Test Course 10
1C - Test Course 11
1D - Test Course 12
1E - Test Course 13
Course Hole Modifier
7E6A5EXX
00 - Hole 1
01 - Hole 2
02 - Hole 3
03 - Hole 4
04 - Hole 5
05 - Hole 6
06 - Hole 7
07 - Hole 8
Course Music Modifier (Also Affects 2 Player Game)
7E6A5CXX
00 - Course 1
01 - Course Intro
02 - Course 4 - Space Valley
06 - Course 5 - Jigsaw Plains
08 - Course 6 - Green Fields
0A - Course 8 - Castles of Cake
0D - No Music
0E - Course 9/Iceberg Ocean
1F - Menu Variant?
20 - Course 2 - Over Water
21 - Silence
22 - Course 7 - The Tricky Stuff
27 - Credits
28 - Demo
29 - Credits Variant
38 - Victory!
41 - King Dedede Battle
56 - Unknown
5B - Lose
Ability Modifier (Player 1)
7ED852XX
00 - Nothing
01 - Rock
02 - Parasol
03 - Fireball
04 - Porcupine
05 - Tornado
06 - Tire
07 - Spark
08 - High Jump
09 - Freezie
0A - UFO
0B - Possible Unused Beta Cook Freezes upon use
0C - Unknown Freezes Upon use
0D - Unknown Freezes Upon use
0E - Unknown Freezes Upon use
0F - Unknown Freezes Upon use
13 - Unknown Freezes Upon use
14 - Unknown Freezes Upon use
15 - Unknown Freezes Upon use
16 - Unknown Freezes Upon use
17 - Unknown Freezes Upon use
18 - FF Freeze Instantly
Ability Modifier (Player 2)
7ED854XX
00 - Nothing
01 - Rock
02 - Parasol
03 - Fireball
04 - Porcupine
05 - Tornado
06 - Tire
07 - Spark
08 - High Jump
09 - Freezie
0A - UFO
0B - Possible Unused Beta Cook Freezes upon use
0C - Unknown Freezes Upon use
0D - Unknown Freezes Upon use
0E - Unknown Freezes Upon use
0F - Unknown Freezes Upon use
13 - Unknown Freezes Upon use
14 - Unknown Freezes Upon use
15 - Unknown Freezes Upon use
16 - Unknown Freezes Upon use
17 - Unknown Freezes Upon use
18 - FF Freeze Instantly
More new codes
1 Player Dice Roll until you stop them
7E631E00
2 Player Dice Roll until you stop them
7E632001
Inf Lives on King Dedede Challenge (You still die if King Dedede touches Kirby)
7ED7F402
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