Game and Watch's Oil Panic charged with 3 of either:
-Pikachu - down B lightning (can max in one go if you catch under pikachu on a platform)
-Pikachu - neutral b (ball form)
-Zelda - Din's Fire
-Lucas - PK Freeze
-Lucas - PK Thunder
-Ness - PK Flash
-Ness - PK Thunder
-Lucario - fully charged energy balls
-Lucario - forward b (closest range possible)
-Samus - fully charged shots
-ZSS - downsmash (any charge)
-Rob - optic blast (charged)
-Pit - arrows (charged)
(Taken from Omegablackmage's G&W guide, at
http://www.smashboards.com/showthread.php?t=141781)
With 3 of those, it deals a whopping 60%, and is almost a guranteed KO at 0%.
Pretty scary.