just by having the key item from the "all items code" won't work..you have to trigger the event..which is to get the item from the green man in any pokemart after you activated the "event codes" you can down the cheats from the database.
here's the code if you can't find or just to save your time:
CODE!Event Item/Pokemon (Talk to man at PokeMart)
:::After pressing the button combination, enter a PokeMart and talk to the man in green.
::Manaphy Egg - L+Sel
:::Must have a blank space in party.
94000130 FDFB0000
62101D40 00000000
B2101D40 00000000
0000B5D4 00000007
0000B5D8 00000000
D2000000 00000000
:
arkrai (Member Card) - R+Sel
:::Go to the locked house in Canalave City.
94000130 FEFB0000
62101D40 00000000
B2101D40 00000000
0000B5D4 00000008
0000B5D8 00000000
D2000000 00000000
::Shaymin (Oak's Letter) - L+Start
:::Go out the right side of Victory Road, continue to the white rock and Oak should appear.
94000130 FDF70000
62101D40 00000000
B2101D40 00000000
0000B5D4 00000009
0000B5D8 00000000
D2000000 00000000
::Arceus (Azure Flute) - R+Start
:::Go to the place where Dialga or Palkia appeared, and the flute will open up a huge staircase.
94000130 FEF70000
62101D40 00000000
B2101D40 00000000
0000B5D4 0000000A
0000B5D8 00000000
D2000000 00000000
::Roton (Secret Key) - L+UP
94000130 FDBF0000
62101D40 00000000
B2101D40 00000000
0000B5D4 0000000C
0000B5D8 00000000
D2000000 00000000
::Regigigas - L+R
:::Have the other regis in your team and fly to the snow city then go to the temple
94000130 FCFF0000
62101D40 00000000
B2101D40 00000000
E000B5D4 00000104
00020001 00000001
00000001 43790000
7610FCA7 14A7FA53
B0EB31B5 BB1F70B4
6053FB54 D0947406
E3A9FC7D 67CF150A
B491738F 5413FEE3
EE507A2D C81E045A
A02CA8DD 7438687D
2AB50AD7 F54F58CB
A6674657 C9410792
48E4A95C 9D7C55BD
A938D69C E24B9F87
D5077CB6 FE636E4D
4C58D45B F308F79F
D4E35429 3CAF223C
91B04F41 8DA31701
ABFE72D8 9C313843
AC2141C6 1EFDD28A
B7CD78A9 37744A30
DEA80C88 92F95736
22317837 D4E459C1
82413E98 FF91B194
3CD5D027 02E7D2AB
D3DE107D DD1B4469
742B3167 A857A728
138B2BCE 26D8ABF6
975673D6 C1B333EB
D8372D49 062303D5
EEB0FDA5 0AB9A8B3
474E9945 00000000
00000000 00000000
00000000 00000000
D2000000 00000000
:
oketch Application Stop Watch (L+R)
94000130 FCFF0000
62101D40 00000000
B2101D40 00000000
0000B5D4 0000000B
0000B5D8 00000017
D2000000 00000000
:
oketch Application Alarm Clock (L+R)
94000130 FCFF0000
62101D40 00000000
B2101D40 00000000
0000B5D4 0000000B
0000B5D8 00000018
D2000000 00000000