Cheats
Enter the following in the cheats/passcode menu:

FROGGIE - Wild traffic.
CHZGUN - Cow missiles.
SMASH# or SMASH## - Replace # with 5, 10, or 15 for that multiple of Smash Points (in the thousands).

Savage Banner
You must beat the game once. At that point you can purchase him from the move shop for 1 million smash points.

Hard Difficulty
Finish the game on any difficulty.