This achievement is awarded for completing Streets of Rage 1, 2 and 3 on any difficulty as any character (Apart from Streets of Rage 3, the only way you can finish this game completely on easy is to select the Japanese version as the EU/US version on easy is cut short and requires Normal mode to finish completely).
Achievements are only awarded in local mode. If done on easy you should have no problems with any of the games using any character but for the smoothest run I'd suggest Axel in each game. He's the most all round character and his Grand upper/Bare Knuckle move in 2 and 3 makes him quite formidable. You use this move my tapping forward and the punch button at the same time. As for the first game, keep your special (A button move to call for reinforcements) for the bosses of each stage.
Another little tip is a reminder that you can save this game at any point, so if you reach a dangerous section of the game, simply save your state and if you feel you could have done it better reload your save.
Per Allgorhythm's comment RE forcing a save can help some players pop the achievement.
"Press the back button when the credits are rolling to force a system save."
People are reporting success regardless of difficulty/region
I played Streets of Rage and Streets of Rage 2 on Europe/Easy and Streets of Rage 3 on Japan/Easy and it unlocked for me :)
Posted by OneSeventyOut on 16 Nov 15 at 11:05
As of today, 05/05/16, I can confirm that you can complete the US version SoR1 and SoR2 on easy and the JP version of SoR3 on easy and get the achievement, I just got it this way.
Posted by danlher360 on 06 May at 03:17
For those who want the easy answer to this achievement and finishing all 3 games, you can just use the level select cheats.
Level Select - SoR1 (thanks to RuukuSukotto for adding this in comments)
At the title screen (The screen with 1 player, 2 player etc...), move the cursor to OPTIONS but don't select it. Hold A + B + C + RIGHT on Controller Two and press START on Controller One. Now enter the OPTIONS screen and look for two new options, "Players" and "Level Select".
Level Select - SoR 2
To do this you will need to have two controllers. Make sure you're on the screen that says 1 player, 2 players, Duel and Options. On the second controller move the cursor arrow down to Options then hold buttons A and B and press start. On the first player controller, you should be on the Options screen with an extra option. That's the option where you can select your stage.
Level Select - SoR 3
At the menu screen highlight Battle with the cursor. Hold Up and B and you will now be on the Options selection, press the Start button while still holding Up and B and you should hear a chime indicating the cheat worked. At the bottom of the options screen you'll see Round Select. Select your round, exit options and select one player and your character and you will begin on the level you selected.
(These are the Sega MegaDrive/Genesis cheats so by default on Xbox A, B and C will be X, A and B respectively so it depends on your controller configuration.)
***Important Region Update***
There are now people reporting that the region does not in fact impact on this achievement popping. In my personal experience and in the case of friends who have finished it this was not the case. There are two possibilities, either this has changes since I have unlocked these achievements last, or the achievement itself is just buggy and very inconsistent.
I would personally recommend you clearing them all on the same region setting but if you don't want to then you can try on different settings. Just please read the other region/difficulty information above in terms of the third game missing levels on certain difficulties with certain regions.
***Old Region Update***
You must finish all 3 games with the same region settings. You can't finish 1 on Japanese and the other 2 on US. Probably the reason so many people weren't getting this. :)