Team Healer (チーム回復だま, chīmu kaifukudama, Lit: Team Recovery Ball) is an item introduced in Super Smash Bros. Brawl. Its main use is in Team Mode, where a player can heal a teammate by throwing the item at his/her character. However, opponent characters can get hit and may be healed as well, although it has a chance to damage non-teammates instead. Smash attacks seem to be able to damage opponents, while tilt throws appear to heal them. The amount healed is based on the amount of damage the target currently has.
In Super Smash Bros. Brawl
A healing item. Hit a teammate with this item in Team Battle to reduce your ally's accumulated damage. You can throw it at an enemy, but any damage inflicted will be minimal, so you're better off using it to help your friends. Oh, and one more thing--you can't reduce you own damage by tossing the item up and letting it hit you. Sorry.
In Super Smash Bros. for Wii U and 3DS
An item exclusive to team battles. If you throw it at injured teammates, it will reduce the damage they've taken so far. It can be used against your foes as well, dealing a little bit of damage, but it can sometimes heal them, too. That's the last thing you want!
If you have selected the Ice Climbers, this will work on the computer controlled character, even if there are no teams (e.g. Training mode) or there are no other players on your team. It's simple enough to press the Grab button during a jump to drop it directly on him or her.