Super Mario All*Stars

Super Mario Brothers:

Reset high scores:
Press A + B + L + R on the title screen.

Super Mario Brothers: The Lost Levels
aka: Super Mario Brothers 2:

Reset high scores:
Press A + B + L + R on the title screen.

World 9
Play through worlds 1 through 8 without using a warp zone. Worlds A through D and the end of the game are after world 9.

Fireworks
Grab the flagpole when 2, 5, or 7 appear as the last digit of the time remaining.

Flagpole extra life
Accumulate coins until the total is a multiple of 11. Grab the flag pole when the last digit of the timer matches the multiple.

Multiple extra lives
Begin the game as Mario. Walk towards the first set of bricks that are floating in mid-air with a Koopa Troopa walking inside. Hit the "?" block to release the Mushroom. Bounce the Mushroom over the last block to take it, but do not bounce out the Koopa or scroll the screen past the first few brick columns. Break the second and fourth bricks, leaving the Koopa jumping on the fifth brick. Stand on the empty "?" block. Hop on the Koopa. Mario will begin bouncing on the Koopa shell, eventually collecting a large number of extra lives.

Warp zones:

World 1-2: Move right to reach the second pipe. The warp to World 3 is near this location.

World 1-2: Jump over the exit pipe of this stage and walk over the ceiling. Keep moving right to find the Warp Zone to world 2.

World 1-2: Jump over the exit pipe of the stage and go down the next pipe. From here, move all the way to the right. Move over the top of the screen to find a warp to World 4.

World 5-1: Move right until reaching two brick platforms in mid-air (immediately before a large brick wall). The far right brick in the upper platform has a vine. Jump off a flying Koopa Paratroopa to reach it and climb to the warp to World 8.

World 5-2: Move right, past the first two upside-down pipes until another hanging pipe appears. Move right and find a big brick object next to some elevators. Use the elevators to hit the farthest right brick in the stack to release a vine leading to a warp to World 7.

World 8-2: The third upright pipe is a warp to World 5-1.

Super Mario Brothers 2:

Restart level
Pause the game and press L + R + Select.