The Gameboy is a weird beast: the first (semi)-viable portable system, it came in to being near the end of the NES's run, and co-existed for a number of years alongside the NES and the SNES. It was home to new games, ports/related-releases of SNES games*, and a lot of early-NES remakes.
Today we turn our attention to the more-advanced yet less-color version of one of those early-NES remakes: prepare to put up your gray hand-held dukes with...
The NES Double Dragon and Gameboy Double Dragon
The top 8 most notable differences I, uh...most noticed:
1: Double your Dragons, double your fun!
Unlike NES DD, the Gameboy version lets you and a friend "Dragon" together. (Of course, to do so you need a second gameboy and a second copy of the game, but what's doubling your expenses when you can get Gray Billy Lee and Gray Jimmy Lee to team up?)
2: I (seven-hearts) Double Dragon
! aka, "Everyone starts with 7 hotels and one million dollars."
No longer do you have to "earn" every attack -- even your basic uppercut. In GB DD, you'll be spin-kicking and hair-pull-throwing from the first screen onwards.
3: Or should that be Double Kangaroo
While you come equipped with a Jump Kick in the Gameboy version, the game's slightly slower speed makes Gray Billy Lee's leaping seem a lot more flighty and floaty.
4: Losing your Bat is for the Birds!
Like the arcade version, you're occasionally allowed to hang on to your weapon for more than one enemy-type on the Gameboy.
In this case the first screen's Williamses bring a bat, which you can continue to use against the following Lindas (though for some reason it disappears after you beat the Lindas).
And hey, speaking of which --
5: No Perm for Linda!
Gone is the Adrienne Barbeau 'fro and jumpsuits of the NES version; Linda's combat attire is now a sporty ponytail and a miniskirt.
6: The Hunchback of Lopardame
Evidently chucking barrels has thrown Lopar's back all out of whack, to the point where he might as well answer to "Igor"
7: Silly Shadow Warriors! Conveyor belts are for kids!
The first area of Level 1 still ends with a door to a warehouse, but the Gameboy gives you a much more free-scrolling brawling area. And instead of a conveyor belt, there's a huge pit to knock people into.
And once you've bested those enemies, ANOTHER door opens, revealing...
8: The Gameboy game only has 1 level* (or, it might as well)
Gameboy Abobo will end you, end of sentence, full stop. His NES counterpart could be jump kicked to death with fairly little problem, or you could trick him into sliding off the conveyor belt.
But on the Gameboy, not only does Graybobo await you in his non-bottomless-pit room, but his battle technique is almost flawless. Even if you jump kick him, he'll smack you before you can recover to jump or slide away.
I've had some luck with the standard beat-em-up tactic of trying to sneak in below his Z-axis, and hit him as he moves on to the same plane as you, but even when using your mighty back-elbow-punch, he manages to grab and beat you frequently enough that you lose health before him.
*: I've subsequently found out that, in defiance of every lesson that beat-em-ups have ever taught me, Abobo is most vulnerable to repeated punch combos, due to Billy Lee's slightly supperior punching-range. Seriously, what beat em up boss is weakest to your most basic attack!?
Well, that about wraps it up...
Having hit a bulbous balding brick wall known as Abobo, I can't comment any further on the Gameboy Double Dragon, but I hope you've enjoyed this comparative trip down urban decay brawling lane!
— carlmarksguy, 2015-02-06