Topic: Difference between NES/SNES Mega Man to Game Boy/Color

Hello, world! I have the question for all of you if you may help me. I own Mega Man and Mega Man II from the NES on my 3DS, but I know that there is a Mega Man game on the Game Boy. I am planning on buying the other four Mega Man games that were released, but I would like to know what are the differences between the NES and SNES Mega Man games and the Game Boy and Game Boy Color games. Mega Man II to VI are coming from the Game Boy to the 3DS along with Mega Man Xtreme and Xtreme II from the Game Boy Color. Are they just the exact same games from their NES/SNES counterparts, or do they have a different story line and/or gamplay? I want to buy the NES and SNES games, but I'd also like to buy the Game Boy games if they are different in the story and/or gameplay, not just about the color and graphics.

Mega Man games are all fairly similar. The Game Boy games 1-4 use the robots from the NES/SNES 1-8. So Mega Man 1 for the game boy uses the robots from Mega Man 1 and 2 from NES. Gameplay is similar, story is similar, but I wouldn't call them exactly the same, but they are not really stretches from the common formula. I plan to buy all the NES games, as well as all the Game Boy games, just because the formula is fun, and I'll take it in as many different iterations as I can.

Levels are similar themed but the maps are different.
Dr. Wily's Revenge features four of the MM1 boss and four boss fights (just the boss) from MM2.
Mega Man II, III and IV features four bosses from the same-titled NES game and then four from the one-higher-numbered NES game.
(MM4 GB was made in 1993, so only MM6 existed up to that point)
Mega Man V used all-new enemies.
Bomb Man and Guts Man from MM1, Gyro, Star, Wave and Gravity from MM5 and the MM6 bosses never appeared on the Game Boy.

As to game features.
MMII added sliding and Rush (first appeared in NES 3)
MMIII added the charge shot (first appeared in NES 4). The first GB game to allow Mega Man to replay levels (I guess if you want to farm E-Tanks), though once you reach the second set of four levels, you can't go back to the first four.
MMIV added letter-collecting, Fliptop and Beat (first appeared in NES 5). It was also the first MM game to have P-Chips (money Mega Man could spend between levels, maybe at Game Over, I forget). It was also the first GB to allow Mega Man to go back to the first four levels after unlocking the second four levels.

The Game Boy games reuse boss characters from the NES originals, but the layouts of the levels are different.
GB MM1 has 4 bosses from NES MM1 + 4 bosses from NES MM2.
GB MM2 has the remaining 4 bosses from NES MM2 + 4 bosses from NES MM3.
GB MM3 has the remaining 4 bosses from NES MM3 + 4 bosses from NES MM4.
GB MM4 has the remaining 4 bosses from NES MM4 + 4 bosses from NES MM5.

GB MM5 breaks this formula, as it has 8 all-new boss characters exclusive to this game.
Still, like I said, in GB MM 1 to 4, all levels are laid out differently from their NES counterparts, and the Wily levels (and final bosses) are all original and exclusive to the Game Boy games.

Everyone's answered your question about the classic series so I'll just respond to your question about Xtreme: like the other portable mega man games they mash up two X games into one, but unlike those the levels are more or less direct lifts from the console versions. They're scaled down, of course, but it's pretty disappointing that a full redesign with the system's capabilities in mind didn't happen like it did for the classic series. As such they really just feel like lesser versions of the originals, and imho they're SIGNIFICANTLY lesser. (They also look like poopoodookie.)

There are some new bosses scattered around the games and a different storyline, so there is that, but a portable X game could have been so much better than what we got.

Come to think of it, Dr. Wily's Revenge didn't have any underwater sections, so it's surprising they programmed the underwater physics just for the Bubble Man fight scene.