Hammer
Hammers are items and a special move commonly found in many Mario games. They've been around ever since the original Donkey Kong, in which they were used to smash barrels rolled at you by Donkey Kong. They are usually thrown by the Hammer Bros. and other enemies.
Item
In Super Mario RPG: Legend of the Seven Stars, Mario's first (and weakest) weapon is a called the Hammer. Mario received the Hammer after he beat the Hammer Bros. blocking the exit of Mushroom Way (In fact, the weapon has their insignia on it.). The mighty plumber used this weapon to pound enemies, at least until he found the Noknok Shell. When equipped, the weapon adds 10 attack points to Mario’s attack rating.
In Mario & Luigi: Superstar Saga, they are crafted by the Hammerhead Bros. out of Hoohoo blocks. They are used to smash rocks in your path, defeat enemies in battle, and hit buttons and switches. They can later be upgraded to Super Hammers and, ultimately, Ultra Hammers. They can also be used to flatten Mario so he can fit into small spaces and to bury Luigi so he can travel under gates.
In Mario & Luigi: Partners in Time, two Hammers are given to Baby Mario and Baby Luigi by the L33t Hamm3r Broz. These weapons can be used to tunnel underground (a useful technique when searching for Beans) and hit switches. In battle, Baby Mario and Baby Luigi can use their hammers to attack enemies (and potentially stun them, rendering a monster inactive for a few turns).
In Paper Mario and Paper Mario: The Thousand-Year Door, Mario receives the Super Hammer and Ultra Hammer as he progresses through the adventure.
Hammers are a powerful item in Super Smash Bros. and Super Smash Bros. Melee.
Hammers make an apperance in Mario vs. Donkey Kong 2: March of the Minis where if a Mini-Mario touched one, they would start slamming the hammers up and down, defeating any enemy nearby. The hammer music from Donkey Kong would play also.
Move
Hammer is a move and a weapon mainly used by Mario, Luigi, and Hammer Bros. in many games starring as one of the first moves introduced to the Marioverse. It wasn't used again for a while following Super Mario Bros. 3 until it was reintroduced in Super Mario RPG: Legend of the Seven Stars. In this game the Hammer was the the weakest of Mario's weapons however. Then it was used in Super Smash Bros. and Super Smash Bros. Melee as a universal move used by any character. It became a major move in Paper Mario and Paper Mario: The Thousand-Year Door as it became an alternate to Jump. Some enemies could exclusively be beaten by using the Hammer. Mario & Luigi: Superstar Saga and Mario & Luigi: Partners in Time soon followed this formula.
In Donkey Kong Mario could destroy barrels thrown by Donkey Kong and defeat fire enemies. It is used in a similiar style in the Super Smash Bros. Series. Mario is not invincible when using it, however. If attacked from the back, he will still lose a life. Mario also cannot climb or jump while wielding the Hammer.
Super Mario Bros. showed it being used by Hammer Bros. and were hard to dodge, especially in pairs. They have an unlimited supply of Hammers, just like Lakitus. After watching the Hammer Bros. use it so many times, Mario and Luigi soon learn how when wearing a Hammer Bros.' Suit in Super Mario Bros. 3. When wearing the suit, they gain all the characteristics and abilities of the Hammer Bros.
Super Mario RPG: Legend of the Seven Stars reintroduced it. However it is one of the weakest moves and it rarely used after finding the Noknok Shell.
Paper Mario and Paper Mario: The Thousand-Year Door gave the move much more focus and was the only way to defeat certain enemies.
In battle, Jump couldn't work on every single enemy, so the Hammer was introduced as an alternate. It worked on all enemies and was always stacked damage, proving useful against fire, spiked, and high defense enemies. There was one flaw to it though; it didn't work against air-bound and ceiling attached enemies. With a special badge, it could be used on all enemies, namely Hammer Throw.
Outside of battle, it can be used the break certain big blocks. The type of block Mario could break depended on what type of Hammer he had. The move, Spin Hammer was also introduced in Paper Mario: The Thousand-Year Door as a way to destroy even bigger blocks. The Red Block was removed from Paper Mario: The Thousand-Year Door, however.
It was used in Mario & Luigi: Superstar Saga and most recently, Mario & Luigi: Partners in Time. Although the move wasn't used as much compared to the Paper Mario Series. Instead of blocks, there were rocks though. Unlike the Paper Mario Series battle system, each Hammer upgrade didn't affect in-battle damage and attack power.
In Mario & Luigi: Partners in Time, new Hammer techniques were introduced to Mario Bros. and helped find Beans.
