Codebreaker U.S. Codes:

Enable [EUR]
00008193 000A
100008B0 0007

Enable [US]
000093DD 000A
100008B0 0007

Transparent
8200055C 0000
Infinite HP
8201327A 270F
Maximum HP
8201327E 270F
Infinite MP
8201327C 270F
Maximum MP
82013280 270F
Max STR
82013282 270F
Max CON
82013284 270F
Max INT
82013286 270F
Max LCK
82013288 7F00
Max Gold
82013290 423F
82013292 000F
Max Experience
8201328C E0FF
8201328E 05F5
Reset Game Timer
820000AC 0000
820000AE 0000
Sprint x2
D0000020 0010
8200052E 0002
D0000020 0020
8200052E FFFD
Infinite Double Jumps (Note 1)
720004F4 1006
320004F4 0002
Always Rush/Guard (Note 2)
32013261 00F4
Weak Final Boss
7200140C 05DC
8200140C 0000
72001598 07D0
82001598 0000
Have all Items
42013294 0101
00000010 0002
Have all Equipment
420132B4 0101
00000034 0002
Complete Soul Set
4201331C FFFF
00000032 0002
---------------
All Abilities
82013392 FFFF
32013394 00FF

or

Use one of a pair at a time. Save then use the other of the pair, if you like.

Have Grave Keeper ability (Backdash) 32013392 0010
Have Skeleton Blaze ability (Slide) 32013392 0001

Have Malphas ability (Double Jump) 32013393 0010
Have Kicker Skeleton ability (Jump Kick) 32013393 0001

Have Hippogryph ability (Air Jump) 32013394 0010
Have Galamoth ability (Time warp disabler?) 32013394 0001
---------------
All Enemy Data
420133A0 FFFF
00000017 0002
Complete Map
420000B6 FFFF
0000013F 0002
Access Warp Gates (Note 3)
74000130 03B7
32000064 0007
32000378 00FF
Unlock Special (Note 4)
32000060 000F
320000A1 0001
Open Mist Door [Press R+B+Up] (Note 5)
74000130 02BD
8200037E 9871

Note 1: You must have the 'Double Jump' ability turned on.
Note 2: This code combines attributes Black Panther, Final Guard, Undine(default) and Skula(hold Down+Jump to Walk underwater.)
Note 3: Enter Map screen then press Start+Up to access Warp Gates.
Note 4: To access Boss Mode you must Save your game with this code on.
Note 5: Press the required button combo when in front of the Mist Door.