Goomba	Defeat Goombas by jumping on top of them.
Koopa Troopa	They will retract into their shells for a while if you jump on them or hit the block they are standing on from underneath. During that time, you can touch the shell to kick it.
Koopa Paratroopa	Jump on top of them to make them lose their wings.
Buzzy Beetle	Make them retract into their shells for a while by jumping on them. You can kick the shell at other enemies. You can’t defeat them with fireballs.
Hammer Bros.	Hammer Bros. will attack you by throwing hammers.
Lakitu	He throws Spiny eggs at you from high above in the sky.
Spiny	These are Lakitu’s pets. You can’t jump on them.
Piranha Plant	Beware of these man-eating plants that live in pipes. Mario will be hurt if he touches one of them.

Note: There are even more enemies to find in the game than those listed here.