Select the third game type on the main menu. (Thanks Omfamna) Skip through a ton of text with A. Then skip the tutorial by pressing start and selecting top option.
On the first fight just keep moving your character to where the enemy is by selecting the top option and defeat them.
Second fight move forward, fight first soldier, then move forward again to show 3 enemies. Attack the front guy that is red and black. Defeat him and achievement unlocked.