From the Super Mario Wiki
The Giant Bob-omb is an item that is used in Super Mario Strikers and Mario Strikers Charged. It is similar to the Bob-omb items, only instead of several Bob-omb's falling in a row, the Giant Bob-omb falls on one spot and explodes, hitting anyone nearby. However, it does affect the user's teammates as well, so the item should be used with caution. Wario may also use this in one of his disappointment scenes in Mario Strikers Charged Football, in which he pulls out a Giant Bob-omb, which explodes on him.
Giant Bob-ombs also appear in Mario Sports Mix in the dodgeball game called Bob-omb Dodge and are more dangerous than ordinary Bob-ombs. They have a wider blast range then the normal Bob-omb in this game and cause twenty-five points of damage to the players.
 See also