This can be done in offline multiplayer with one or two controllers. The same method works for the 'Won on 8 Player Multiplayer battle' Achievement - see my guide for that Achievement for more details.
From the main menu:
- Select
Standard.
- Pick
VS Battle.
- Select
Multiplayer Battle.
- Set
Player to 4 and Sets to 1.
Two controllers (the easiest method):
- Set
Com Level to Off.
- Select any stage.
- Have the second controller join in.
- Select both characters and press
to select
None for players 3 and 4.
- During the match,
lay a bomb with the second controller and allow it to
kill the second player.
- After the match ends, the Achievement will pop!
One controller method (still easy):
- Set
Com Level to Weak.
- Select any stage.
- Select your character.
- Set the
second character to COM and select the character.
- For players 3 and 4, switch the
COM option to
None.- Start the match and
defeat the sole computer opponent. If you fail, select
Battle Again and try again until you win.
- The Achievement will pop after your victory.