This Seeking Tech guide will show you how to easily unlock the Memphis Bomb Princess trophy and achievement in Metal Slug XX.
To unlock this, you need to do the following: “As Eri, kill 10 enemy soldiers at the same time with grenades.”
Use the following video as a visual aide:
To start off, head to the beginning of Stage 2.
When heading down the elevator, jump to the right and ignore the enemies. You should then destroy the right-most crate without hurting the enemy nearby.
Another crate should then drop on the left side of the screen, next to the soldier with the siren. Break that crate to trigger a fight with the 100 Morden Soldiers.
Keep using your bombs and you should be able to unlock this trophy.