LEGO DC Super-Villains

The "Fight at the Museum" level is perfect for this achievement. You don't really have enemies to fight until you get to the boss fight. Use Black Adam, because when you get hit, your hearts regenerate, so run around to get them back. You get the pop after the last scene.

Also, I'm not sure if this would work because I didn't try it, but alternatively, if you're struggling with it (I doubt it because playing as Black Adam is like playing on easy mode), you can play as Superman since he's invincible. Or if you've beaten the game you can slap invincibility on your created character.

If this is yout first time through, you'll also unlock:

So the level I did it on without even trying was the Shazam DLC 1 level, “Sivana Escape”. There are no enemies to fight at all. Besides Sivana himself, and all three encounters are quick time events. Easy peasy.

The ideal way to get this achievement is to play 2-player split screen mode and complete one of the last 5 "bonus" missions - these missions are shorter and easier to complete. Then, make sure you remain as an invincible character - like Green Lantern or Superman - for the entire mission. As long as you don't jump off the map, your character will automatically generate health and stay alive for the whole mission. Use the second controller or second player to complete tasks required by non-invincible characters. At the end of the mission, the achievement should pop.