Why?!
 

Got pretty far with Donatello on the GC version of the game. But the last level is near impossible, the Elite foot, the mystics, Baxter and the mousers. By the time I got to Shredder I had one life. But the question is: How come there arent codes for infinite lives, or infinite shurikins for Donatello.

Also, what are the improved weapons? And can I use the 2x improvements more than once?

you cant use it twice, to my knowledge any way.
I know when I got up to that point I wished that there was a code for infinite live, but some how I made it through.

Are you playing on Normal difficulty or.....
Well if you are then:
When you fight Elite Guard, Mystical Ninja and the giant Mousers. Just use the E button all the time (E button=Fast movement) And when either the Elite, mystic or the mousers are done attacking you just hit them with everything you, try to make as many combos as you can. With this technique i made it to shredder with 5 lives left and that was with Mikey. And what concerns Baxter, I think there's is a thread about beating him somewhere in this Forum.

And sorry, don't know any codes :|

I've done the same thing, on easy, and i can only get there with one life left.

The easiest way to take Shredder down is to save all the shruken's you can.... at least that's my theory. i gave up on that game.

My friend came over today and we beat the game on Donny's game, shurikens helped, and we got there with 3 lives left, and didn't die fighting Shredder.

My next question is when the last stage of Justice is highlighted, to the right there is another stage, what the hell is it? I wasnt given the option of getting to it.

Beat the game as all four Turtles, when you beat it as the fourth, you'll go to that room and fight Saki.

Hmm, who are you playing as???

I've never played with either don or raph, so i don't know if they're any good to play with.

It's about skills too of course :D

I have beat the game with Leo and Mikey both on Normal!

It's still hard, i lost 2 lives when i fought shredder. I think the best way to beat him is, To throw a Shuriken at him, and when the shuriken hits him, then Attack with all the combos you can!!

Heres what i did:

I collected electric shrukens and when they hit him (You have to be near him) GO CRAZY!

yes, that's the way to do it hehe. I know i did

I beat the game with all four turtles on Normal. I had the easiest time with Don, 'cause he's just the best character to play with because of his incredible reach (which gives him a definite advantage over his brothers.)

I had the hardest time with Raphael because his weapons are so damn small and short, his attacks suck and his reach is pretty much non-existant. (Funny though, I beat Saki with Raph...But I used all the Gembu Turtle Powers and shurikens...And lost five lives in the process...) :D

Yeah. Boy, was Oroku Saki tough. Donnie was almost a walkthrough. But Splinter OMG :o. His offensive in fully increased from the start, If not more

I beat Oroku Saki once. Only once. He's just too tough. Even when I beat him it was with 2 Players and using the "infinite explosive shurikens" code for Mikey.

I still haven't beaten challenge mode and I don't think I'm going to be able to. I was doing pretty good and I even beat Shredder without too much work, but Saki beat the crap outta me. I was dead in less than a minute. :(

I have yet to fight Saki with Don, though. I may be a little better then. Don is the character I can use the best.

hmmm, Yeah Oroku Saki really is a toughie. I used all 6 lives. and I only had 20 regular shurikens

I cannot get past Baxter

You just have to be patient. actually there's a Thread about ''How to beat Baxter'' in this forum

Quick 'n Dirty version: Dodge his attacks, jump attack his face. Good luck!