I agree Battletoads use to drive me insane I also had alot of problems with Super Gouls and Ghost fro SNES.

You beat SMBB's story mode easily?  You got crowns on all eight worlds by not using a continue to get World 9 and then got a crown on World 9 to get World 10 and then beat all of those?  If you did all of that then you would not be saying how easy it is.  :p 

Yeah I would have to say Ninja Gaiden (Black or Sigma, it's the same...).

I died 336 times on my first clear of Normal mode.
I can now clear it without dying but there are 3 difficulties level above normal and I have only tried and beaten hard and things are supposed to start getting crazy in very hard and master ninja difficulty...
The good thing about that game though is that it's not luck based at all so as your skills increase you can play and beat the harder difficulties without dying with little luck involved ( I'm looking at you CoD:WaW BS grenade spamming!!!)

I'm convinced that only 1% of the people who ever try to beat Battletoads finish it. It's ridiculously hard, even if you are familiar with the game. If you're not, you simply don't stand a chance.

i feeel great then i went through the entire game in battletoads...wish i could say the same for super ghouls n ghost :( game gave me nightmares

I was able to play through Contra without dying as soon as I had the Spreads weapon. To even put that in the same breath as Battletoads or Super Ghouls and Ghosts is a joke.

Contra was easy!

Touhou

This is the hardest game ever, just try it... ,
http://www.lemon64.com/?mainurl=http%3A//www.lemon64.com/games/details.php%3FID%3D2769

 Thank you! I'm always confused when people say the original Contra is hard. I haven't played that game in years but am confident I could beat it again in less than half an hour using only 2 or 3 lives, just as I used to when I was a kid.

Fixed. Mega Man 2 can be challenging, especially if you're new to platformers and don't know the weapons or weakness chains, but to say it's anywhere near the level of Battletoads or Ghouls and Ghosts is ludicrous. I mean - MM2 actually has passwords, storable bonus items, an energy bar that isn't just for show, and levels that were designed by actual human developers instead of a team of particularly ornery pit demons. And you don't have to beat the friggin' game twice in a row in order to beat it "properly" once.

On the other hand, you could add the PS2 Shinobi, any of the Trauma Center games, or Bayou Billy on that list. Any of those games are, indeed, beatable and even fun - if you've spent years mastering every little quirk so you won't get mercilessly butchered by the next random mook that doesn't want to play along with you.