Super Mario Land 2: 6 Golden coins

Master the Bonus Game
This will get you 3 extra lives every time.
Wait until the heart going into the left hand opening and then drop the claw.
The claw will grab the heart when it comes back out the other side.

99 Lives
Beat the Hippopotamus and Space zones.
Go back to the Hippopotamus Zone and run into the water.
Go left and grab the prize that is worth 50 coins.
Keep repeating this until you get 999 coins.
Then, play the Bonus Game.
Repeat this whole procedure until yo

Easier Game
On the Title screen, press Start to enter the pipe room.
In this room, press Select to get into "Easy Mode." You can then begin  any saved file you wish.

Map Return
Press Start, Select to return to the map without dying.