I think it solely depends on the person playing it. I've heard people say that Contra is easy to beat (even without the code), but I can hardly get past the second level.
For me, all the Super Mario games are easy as pie. I can sit down and beat each one with no problems - either by skipping worlds or playing through each level.

My choices:

Bugs Bunny Birthday Blowout
Chip n' Dale Rescue Rangers
Contra Force
Duck Tales
Dynowarz
Felix the Cat
Guerrilla War
Jaws
Kung Fu
Little Mermaid
Mario is Missing
Mickey Mousecapade
Monopoly
Monster in My Pocket
MTV Remote Control
Power Blade
Puss n' Boots
Rampage
Super Dodge Ball
Teenage Mutant Ninja Turtles 2
Toki
Wacky Races
Wayne Gretzky Hockey
Xenophobe

Some of these games are not that easy

My list

Bad dudes
double dribble
blades of steel
rbi and most sports games
double dragon 2 once you get past the jumping levels
lifeforce with code
contra with code
super c with code

and others of course that are endurance matches with unlimites continues like guerilla war, and ikari warriors

My game was a blowout like 270 to 35

AI is so dumb.  I think you could pick answers randomly and still win.

Guerrilla War, especially 2 player mode, is a very easy mark as stated earlier in the thread... Completed in less than an hour usually.

Bugs Bunny's Birthday Blowout, I usually have 99 lives by the time I make it to the end.

Snow Bros. is also very easy but a joy to play, every time.

1943 and Legendary Wings aren't exactly easy, but they're about as addictive as nes games get.

Basically any game with infinite continues is decidedly beatable. While I wouldn't really call any of the following easy, if you've got a chunk of hours and don't mind beating your head against them until you figure stuff out, you will see the ending eventually (and they're some of my favorites on the console to boot).

Batman
Kickmaster
Metal Storm
Ninja Gaiden
Ninja Gaiden 2

If you're looking for an easy 1 credit/life clear, look elsewhere, but these games are crazy fun, and you can continue to your heart's content. Of those 5, Kickmaster (highly unheralded gem of a game imo) and Metal Storm are probably the easier ones, and Ninja Gaiden doesn't really kick it into high gear until Act 5.

I think most of you didn't read the original post or are just trolling.

River City Ransom. Best fighting game ever. The music is awesome. The bad guys are cool. You can throw rocks, chains, trash cans, pipes, brass kuckles, tires, other bad guys, sticks, and boxes at people. Two player is SO MUCH FUN. It's fun to upgrade your fighting stats. You can buy FREE smiles at Marv's! Stone hands! Dragon Feet! Excaliburs Sword!!!! Sauna!!!!!! hahaha obviously one of my favorite games ever.     Oh and if you like to play Gameboy Mortal Kombat 2 is hands down the easiest final boss ever. Just roundhouse kick non stop and he can't touch you.

Kid Klown seemed really easy the one time I played it.

Hey I'm playing bucky o'hare right now! It's awesome!!! Question though, is it possible to have 2 players play at the same time? On the bottom right above "HI" for "high score", it says "1P" which infers that you can have more than 1 player, or am I wrong?

i like beating friday the 13th in 7 to 10 minutes,younger bro and i like seeing how quickly i can smear that ugly purple freak

Super Mario Bros/Duck Hunt for the win! My whole family played it when I was a kid... even my great grandmother. If they aren't casual gamers, I don't know who is.

Hmmmm, I've never tried, but I believe it's only one player unfortunately. I think it was maybe too much for the system to handle to have all that was going on, good graphics, and a second player.

DuckTales
Bonk's Adventure
Contra
Super Mario Bros. 2
Super Dodge Ball

Yea I think it's one player too. I'm almost through the whole game I think. Boy is bucky a good game!! Thank you Vcube again !!!! I also tried out metal storm and it's pretty unique and very fun as well!

There are lots of troll-y trolls in this thread

Also, shame on you all for not mentioning Space Shuttle Project.

<3 that game