The enemies in this game are considered part of the "8 bits", a "club from evil dreams" (as the manual says[1]), the group of monsters that Wart created with the dream machine.
Regular enemies
Mario and friends can jump on these enemies and throw them away.
Shyguy
Tweeter
The ubiquitous Shyguy is a pushover. Red ones walk in straight lines until stopped but blue ones (pink in the NES versions) pace to and fro in one location.
Even some birds of Sub-con wear masks. Tweeters often attack in groups, bouncing along the ground until they locate prey. Watch out for a large leap when they get close.
Snifit
Gray Snifit
Though they may look like a Shyguy, the Snifit will surprise unwary travelers with a barrage of bullets. Like Shyguys, red ones walk off ledges while blue Snifits (pink in the NES versions) pace back and forth.
Gray Snifits are in a special category by themselves; they stand guard over one location and will not stray. They typically leap straight up into the air before shooting at you. Wait for it to fire before attacking.
Beezo
Ninji
Beezos fly in straight lines and are lightning quick. You can jump on one and ride it, but you must keep moving or you'll fall right off. The gray Beezos from the NES version are replaced with yellow Beezos in later versions.
Up and down, up and down—Ninji doesn't do much except jump, but the jumping makes it tough to sneak past them unscathed.
Hoopster
Trouter
Hoopsters are a ladybug-like insect that like to climb up and down vines. Although they won't hesitate to attack anyone who dares invade their vine, they will absent-mindedly give lifts to anyone who rides on top of them.
Trouters spring up and down in water. You can use them as stepping stones, but don't ride them for too long or you'll be sunk.
Flurry
Bob-Omb
Like a winter chill, Flurries can ruin the best of adventures. Lure them to a platform's edge, then jump over them and watch them slide off.
Bob-Ombs (a.k.a. Bob Omb in Super Mario Advance) like to roam the worlds, but they also hide in patches of grass. If you pull one up, toss it quickly before it explodes.
Pidget
Cobrat
Pidget attacks from the safety of a flying carpet. Once it swoops down, leap on and throw Pidget aside. The carpet is then yours to use.
Cobrats hide in dark places then leap out and attack. Watch for their beady eyes peering out from jars and quicksand.
Pokey
Cactus-like Pokey has four round segments. Don't pick the segments up singly, just throw an item at the bottom one for a quick victory.
Tougher enemies
These enemies are tougher than the previous ones: Mario and friends cannot lift or throw any of them, and they also get hurt by any contact with most of these tough guys.
Phanto
Porcupo
Guardians of the key, Phantos will chase anyone who steals their treasure. If one is hot on your tail, drop the key to make it give up the chase until you pick it back up.
Porcupo is covered in sharp quills that cause damage if touched. This is one of the few enemies that you can't ride on top of, so attack Porcupo with an item or just avoid them entirely.
Spark
Panser
Don't touch Spark, or you'll get a shocking surprise. Attack this electrified enemy with an item to avoid losing health.
Panser's multiple fireballs are a pain. Grab a sprout or enemy and use it to take out the flaming flora from a distance.
Ostro
Autobomb
Speedy Ostro is a double threat, as you must take out both the Shyguy rider and Ostro itself. Pick up the Shyguy and use it to attack Ostro.
This machine makes for an explosive encounter. Autobomb is a wheeled cart with a Shyguy driver. Leap on board and toss the Shyguy, then use the cart to ride over dangerous terrain.
Albatoss
The high flying Albatoss often carry Bob-ombs to drop on you from above. If one flies low enough , you can jump on and ride it just like a Pidget's flying carpet, except you have no control over its movement while riding it.
