Stop Watch
Pull up four large vegetables in Super Mario Bros. 2 and the 5th plant will be a Stop Watch. It will appear for a second and then freeze everything and everyone temporarily. If Mario needs any Small Hearts, this is a good chance to defeat some enemies so they can appear.
The Stop Watch is later seen in the Paper Mario series. When Mario uses this item, if it works it will immobilize enemies for a few turns. It can be bought at most stores and is a fairly common item. A Stop Watch will be making an appearance in Super Smash Bros. Brawl as an item that players can use. When used, all players will slow down, except the user. It can backfire and cause the user to only slow down.
Trophy Information from Super Smash Bros. Brawl
An item that slows down time and your enemies' movements. Only the player who gets the item will move at normal speed. You should enjoy a huge advantage in both attacking enemies and snagging items that appear. If an enemy manages to get to a powerful item first, you'll be able to shield and dodge and keep any damage you take to a minimum.
