Codes!!!
 

PS2

Alternate Costume (Raphael): DMDML
Alternate Costume (Leonardo): LDMSR
Alternate Costume (Michaelangelo): RRLMD
Alternate Costume (Donatello): DDSMS
Attack Power Up (Raphael): RDSRL
Attack Power Up (Leonardo): LMLSD
Attack Power Up (Donatello): DRLDS
Defense Doubles (Leonardo): MRLLM
Defense Doubles (Donatello): SSSMR
Defense Doubles (Michaelangelo): MRRML
Defense Doubles (Raphael): LRMDS
Defense Power Up (Michaelangelo): MSRMM
Change Sound Effects: SMMRS
Power Up Effects Double (Raphael): SLDSM/MSLLR
Power Up Effects Double (Donatello): DMDRS
Power Up Effects Double (Michaelangelo): MMSLR
Power Up Effects Double (Leonardo): LSLSR
Unlimited Fire Shurikens/All Food is Pizza (Michaelangelo): DRDSS
Unlimited Shurikens (Leonardo): SMRDM
Unlock Playmates Toy Data Base: LSDRM
Unlock Splinter for Story Mode: MSRLS
GameCube

Alternate Costume (Raphael): SLSMM
Alternate Costume (Leonardo): RSLMD
Alternate Costume (Michaelangelo): RLSLS
Alternate Costume (Donatello): RRSLR
Attack Power Up (Raphael): RDSRL
Attack Power Up (Leonardo): LMLSD
Attack Power Up (Donatello): DRLDS
Defense Doubles (Leonardo): LDSMS
Defense Doubles (Donatello): MLMLS
Defense Doubles (Michaelangelo): MRRML
Defense Doubles (Raphael): SDRML
Defense Power Up (Michaelangelo): MSRMM
Change Sound Effects: DDDML
Power Up Effects Double (Raphael): LSMMS/RSSSR
Power Up Effects Double (Donatello): MLSDS
Power Up Effects Double (Michaelangelo): RLMSM
Power Up Effects Double (Leonardo): RSDMM
Unlimited Fire Shurikens/All Food is Pizza (Michaelangelo): MSSLD
Unlimited Shurikens (Leonardo): SSLDM
Unlock Playmates Toy Data Base: LSDRM
Unlock Splinter for Story Mode: LSLML
Xbox

Alternate Costume (Raphael): LMSDD
Alternate Costume (Leonardo): RMMLL
Alternate Costume (Michaelangelo): DLDSM
Alternate Costume (Donatello): SRSMM
Attack Power Up (Raphael): RDSRL
Attack Power Up (Leonardo): LMLSD
Attack Power Up (Donatello): DRLDS
Defense Doubles (Leonardo): MLLSR
Defense Doubles (Donatello): LLSMR
Defense Doubles (Michaelangelo): MRLLD
Defense Doubles (Raphael): LSMDR
Defense Power Up (Michaelangelo): MSRMM
Change Sound Effects: LSLSS
Power Up Effects Double (Raphael): SRRLR/LRLMS
Power Up Effects Double (Donatello): SMLLR
Power Up Effects Double (Michaelangelo): SMRDL
Power Up Effects Double (Leonardo): SLDDS
Unlimited Fire Shurikens/All Food is Pizza (Michaelangelo): MRRSL
Unlimited Shurikens (Leonardo): MSSRD
Unlock Playmates Toy Data Base: LSDRM
Unlock Splinter for Story Mode: LLMSR
PC

Alternate Costume (Raphael): SMLSR
Alternate Costume (Leonardo): MSRLR
Alternate Costume (Michaelangelo): MMMSL
Alternate Costume (Donatello): LMSSL
Attack Power Up (Raphael): RDSRL
Attack Power Up (Leonardo): LMLSD
Attack Power Up (Donatello): DRLDS
Defense Doubles (Leonardo): SSRSL
Defense Doubles (Donatello): LRLDD
Defense Doubles (Michaelangelo): LSSDR
Defense Doubles (Raphael): DSRRS
Defense Power Up (Michaelangelo): MSRMM
Change Sound Effects: SLSRS
Power Up Effects Double (Raphael): DLDRS/LMMDR
Power Up Effects Double (Donatello): SDDLS
Power Up Effects Double (Michaelangelo): LMLMS
Power Up Effects Double (Leonardo): LDDRS
Unlimited Fire Shurikens/All Food is Pizza (Michaelangelo): MDMSL
Unlimited Shurikens (Leonardo): SRRDM
Unlock Playmates Toy Data Base: LSDRM
Unlock Splinter for Story Mode: LDRSM

What are the alternate costumes???

sweet, finally some PS2 codes that work....thanks man. THe alt costumes are: Mikey-Turtle Titan, Leo-some ninja outfit, Raph-biker costume, and Don looks like the old toy, Undercover Don, with the long trenchcoat and a hat.

cool... I'm gonna play as Undercover Don :D

I just tried out Splinter and, well.............I hate playing with him. His moves dont seem to be as good and take longer(????) And his grunt gets annoying right away, its worse than the turtles.