Dr. Mario (SSB4)/Down smash
From SmashWiki, the Super Smash Bros. wiki
Dr. Mario's down smash is a breakdancing sweep with low startup lag. It has good range, decent power, and is a semi-spike, making it a good finisher, and also great at gimping recoveries. It also transitions well to the second hit, so it is great at punishing rolls. It is not as reliable a finisher as his other smashes, back throw, clean up special, or sweetspotted forward aerial however due to its low vertical range and merely average power.