Amy's hammer varies in size. It can be as small as her head, or it can be larger than her body. One of its larger sizes was shown in Sonic X Episode 9 when Dr. Eggman destroyed a bracelet she made as a gift for Sonic. In a fit of uncontrollable rage, she whipped out the hammer and flattened one of Eggman's giant robots in a parody of the ancient Japanese game, Daruma Otoshi, and sent Eggman flying into the ocean. In Sonic & Sega All-Stars Racing, Amy's All-Star move has her take out the Piko Piko Hammer. In this case it is much larger than her car. She has also used it in Sonic X Episode 5 in an attempt to break the gang out of Eggman's robot when they were trapped inside it.
History and purpose
Amy was first seen using one of her hammers in the Sonic the Fighters but in a different color scheme. The reason she was given the hammer as a weapon was to strengthen her tomboyish nature (note that this is also the reason why she is a playable character in the game). As a result, she does not punch.
After that, the big hammer became the main weapon of Amy and is a vital of her Hammer Attack techniques. Amy uses her hammer to break objects in her way or to hit Sonic with it. At times she also uses it to simply strike fear into potential enemies. With her hammer Amy is never second best on the battle floor and is able to actually scare the other characters for her strength and fury.
Also, in the game Sonic Advance 3, when selecting Amy as the leader or the sidekick, her partner will also have a Piko Piko Hammer (it does not matter which character is chosen as Amy's partner).
- Amy's Piko Piko Hammer was originally based on a popular Japanese children's toy of the same name. The phrase "piko-piko" is an onomatopoeia for the chirping sound that these hammers make when struck (which can also be heard in several games when Amy attacks). Despite this, Amy has repeatedly demonstrated that her hammer possesses destructive power far beyond that of anything that could be called a toy.
- It has been stated that Amy battles enemies with her hammer to impress Sonic or when in danger.
- The only Sonic universe where Amy doesn't use her hammer as her favorite weapon is "Sonic The Comic", where she uses a bow or a crossbow instead.
- In Sonic Unleashed, Amy's ability to use the huge hammer is underlined when defeating the boss of Shamar, the Dark Guardian. After the level is over Sonic the Werehog exclaims "I know little girls that are better with a hammer than you are! Well, one, anyway."
- Luigi's Squeaky Mallet in Mario Power Tennis\Power Tour looks like Amy's hammer and also both of their hammers are called "toy hammer" in Japan.
- An accessory of Amy's Piko Piko Hammer, made by Jazwares, was released in late-2012 along with Amy.
- The Ultra Hammer from the Paper Mario series bears an uncanny resemblance to the Piko Piko Hammer.
- It is unknown where Amy stores her hammer and where she pulls it out of for use. The question was even parodied in Sonic X and her trophy info in Super Smash Bros. Brawl.
- In the comics, it is said that Amy absorbed the Ring of Acorn's magic, which allows her to pull the hammer from thin air. 
- She also seems to have an inexhaustible supply of Piko Piko Hammers, as proven by Episode 52 of Sonic X, where she conjured up a Piko Piko Hammer out of nowhere just by waving her hand. Decoe made fun of this by saying that Amy had "more hammers than a hardware store."
- Amy seems to have some sort of connection to her hammers, because in the Sonic X comic, when she, Sonic, Knuckles, Tails and Rouge are trapped in a virtual reality by Eggman, Amy says she can't 'feel' her hammer while she's within the illusion.
- In Sonic the Fighters, Amy's hammer isn't referred to as the "Piko Piko Hammer" but the "Magical Hammer".
- In the Archie Comics the hammer isn't indestructible. Amy's anti-self managed to break a normal-sized hammer (not a giant one) with her own version of the Piko Piko Hammer.
- In some games, the hammer can be used to hit Springs, causing her to catapult quite a bit further, and can be used like a spring in Sonic Adventure and sometimes in the Sonic Advance games.
- In Sonic Adventure, a much stronger version of the Piko Piko Hammer is the Long Hammer, of which is obtained from the Egg Carrier (destroyed) if Amy beats her "own" score she set after beating Eggman's 2000pt score in "his" version of the Whac-A-Mole minigame in Story Mode. It is possible that Amy has different "versions" of Piko Piko Hammers, as seen in Sonic Heroes, where she uses the Air Hammer which utilizes the power of the wind. In Sonic Advance 3, she has a huge brown mallet when teamed up with Knuckles, and her normal red and yellow hammers.
- Amy's hammer was mentioned in Sonic and the Black Knight in the final cutscene when Sonic says "Yikes! No Amy, wait! Put down that hammer!". Thus, in the multiplayer mode of the game, Amy is playable and instead of a sword, her weapon is a hammer.
- Amy's hammer has been shown at time having the ability to randomly show pink hearts.
- It makes an appearance in Sonic Adventure 2's Gamecube remake, when she uses a homing attack.
- In Sonic Adventure 2: Battle and Sonic Heroes, the hammer has the opposite color scheme on the hammer head than her regular one; having red ends with yellow center instead of yellow ends with red center.
- The Piko Piko Hammer's modern 3D model in mainstream games differs from the modern appearance shown in the comics, cartoon and some earlier spin-off games.
- In Sonic Battle it is referred to as "Love Hammer".
- The Piko Piko Hammer also appear in Hatsune Miku: Project DIVA 2nd in the accessories room. This accessory is unlocked if the player clears "サウンド"(Sound) in easy mode. It is also Rin Kagamine's favorite item as gift.
- The Piko Piko Hammer is the most recurring weapon in the Sonic series, unless one counts Eggman's Egg Mobile as a weapon.
- In Mario & Sonic at the London 2012 Olympic Games, during a mission that can be given by Amy about Goombas being on a rampage, Amy says her Piko Piko Hammer has no effect on Goombas for some reason, which is ironic since, in the Mario series, Goombas are the basic enemies, which can usually be defeated by being stomped on or even by smashing them with a hammer.