Extra Continues in a One Player Game

Start a two player game. Now, beat up Zitz until all of his lives are gone. When you're given the chance to continue, don't. Now play the game normally as Rash, and when you get a game over as him, press start on controller 2, so you'll play as Zitz. Again, when you're defeated as him, press start on controller 1 and you'll resume play as Rash. By repeating this, you'll have more than 3 continues in a solo game!

Contributed by: Binta 

Farming for extra lives/points

If you want to stack up your points for extra lives, a good and safe place for doing that is in the beginning of level 8 (Intruder Excluder).
At the start of the level, grab the pole and jump up to were the yellow balls are coming out from the right wall. With the pole in your arsenal, you are now able to both bash and hit the balls for points(without it you can't hit them and will instead take damage).
A good place to stand is on the left side, just beside where the balls hit the ground and break. Keep on either smashing them with the pole for 750 points or ramming into them for 2000 points.

Contributed by: raukNroll 

Warp to Level 11

In Level 10 (Rat Race), when you kick the bomb in any of the three "races", the Spazz you've been racing will generally fall down from the top of the screen and hit its head on the girder, sending you to the next segment. You still can hit Spazz in this short while with regular or double-tap charge attacks as usual; if you're able to hit the rat with a Final Smash move before you fall to the next segment, the level-finish music will play and you'll be warped to Level 11!

Contributed by: ElDodo_GF 

Start later in a 2-player game

A variation of the continue later code for 2 player games in Nintendo power I discovered myself. Rather simple....

Start a 1-player game and proceed to whatever level you wish. When you get to the level your friend wants to start in (you could go to level 9 and play that when your inexperienced friend couldn't make it there, for example) You will then start with all continues/lives and start on the level 1P is currently on!

Contributed by: MI4 REAL 

Continue later in game

When you are playing a 2 player game, and one player loses all his lifes, do NOT continue the game, then continue on. When you reach the point your partner wants to continue on, have him press START on the map screen. He will come back, even after his absence!

Contributed by: MI4 REAL 

Warp to Level 8

In Level 6 (Karnaths Lair) in the 2nd Snake pit, climb on the first snake and jump all the way to the right when the snake reaches the height of it's path (don't hit the spikes) there should be a warp on the other side. You must jump over because the warp will disappear before the snake gets there.

Contributed by: MI4 REAL 

Warp to Level 6

In Level 4 (Ice Caverns) when you find the platform that falls when you stand on it, go down near the bottom, then jump repeatedly so it goes back up. There should be a warp formed at the top.

Contributed by: MI4 REAL 

Warp to Level 5

In Level 3 (The turbo tunnel) in the last section of the speed bike obstacle course (where the walls pass REALLY fast) slam headfirst into the 10th wall. That should be a warp. (The correct wall is on the bottom of the island BTW)

Contributed by: MI4 REAL 

Warp to Level 3

When you begin the game, quickly headbutt the psyko pig on the left, then the one on the right, proceed to where the Walker appears, you should see a platform and a pulsating warp. Jump up there quickly!!!

Contributed by: MI4 REAL 

5 Extra Lives

When on the title screen, hold Down, A + B and press Start. This is only valid on the US & European releases and will not work on the Japan version.

Contributed by: Dallas 

Get 5 extra lives

Down + A + B and press Start at the title screen.

Contributed by: Vidyasaur 

Five Extra Lives

Contributed by: Retro