Sega Vintage Collection: Streets of Rage

Simple. Just play through to the end of the second stage of the first game as Adam and defeat the boss. Made even easier if you save your special attack.

Achievement will unlock as soon as the boss dies.

The trick to this fight is to keep the high ground throughout the encounter. Stay directly above the boss as he weaves back and forth. You can then consistently take the initiative by slowly inching down until you get on a level plane. Keep matching his his left-right movements as you inch down on him.

Using this method of creeping in from above, you should be able to consistently get in your attacks before he's able to swipe you. With a little patience, you should be able to take him down without taking any damage.

Play through the end of Round 2 of Streets of Rage with Adam. Then you'll encounter a Souther. If you jump kick with +, he'll do a quick blurred attack, usually missing you. Now simply turn around and mash . With this tactic, it'll be very easy to defeat him.