Hi!
Here's some info on some characters from Shugo Chara!
Amu
* Height: 152 cm, Birthday: September 24, Blood type: O
* Guardian Chara: Ran, Miki, Suu
Protagonist. A student of Seiyo Elementary (fifth grade at start of story). Her charm point is her "×" shape hair clip. During Chara Change and Chara Become her hair clip changes (Ran→Heart, Miki→Spade, Su→Clover) and the Chara Become forms are named: Ran→Amulet Heart, Miki→Amulet Spade, Su→Amulet Clover. The characters Amu becomes are good at certain activities like Amulet Heart who is athletic, Amulet Spade who is good at Art and Crafts, and Amulet Clover who is good at cooking(all house-work in general).
Amu was seen as a cool and stylish girl and has become popular at school but what she really is is just a shy, gentle, docile and extremely normal girl. The main reason for this misunderstanding is the trendy punky clothing her mom buys for her. One night she wished she wasn't the type of person she currently was, and on the next morning, 3 Guardian Eggs appeared. She has a crush on Hotori Tadase, the Kings Chair of Seiyo Elementary's Guardians. She confessed her feelings but was rejected.
At first, she rejected the offer to join the Guardians with the reason that she does not want to wear the royal cape. But on Tadase's sincere invitation, she joins the Guardians under a special position, the Joker. On joining the Guardians, she received the "Humpty Lock", a locket with a four leaf clover decoration. Nadeshiko stated that the last king left it and said 'entrust this to the joker whom comes with three Guardian Eggs'. Later on, it was explained to her that the Joker's duty to hunt X Eggs.
It is seen that Amu might have a slight crush on Ikuto as whenever he touches her, she blushes. In volume 5, Amu goes on a date with Tadase, which shows a little bit more development of their relationship. She also was confronted by Ikuto, on her date, resulting to a confession from Ikuto saying the actual reason he bothers her is because he is interested in her.
Hotori Tadase

* Birthday: March 29, Blood type: B, Allergic to Pollen
* Guardian Chara: Kiseki
The boy the same age as Amu who serves as the K Chair (Kings Chair). His alias is "Prince", and is Amu's love interest. Whenever he is called "Prince", his character changes into a violent, egotistical king who wishes to rule the world. Because of this, he does not do Chara Change with Kiseki unless it's absolutely necessary. Actually, he too is a shy person and is not a public speaker. So he wished to become stronger and become another character, much like Amu. He, along with the other guardians, tried to get Amu to join because of a prophecy about a girl who will appear with three Guardian Eggs. He lives in a traditional Japanese house. He had a precious dog named Betty (name learned in volume 2 of the manga) who died recently, and is still upset about it.
He claims to have a crush on Amulet Heart. At first he is about the same height as Amu, later on he grew taller. At one time he lost confidence as he can't seem to find the Embryo at all. At that time he was affected by the Black Diamonds CD, causing Kiseki to change to an X Egg. Luckily Amu helped him out of this crisis and after that he is able to do Chara Become.
Nadeshiko Fujisaki (real name Nagihiko Fujisaki)
* Birthday: July 4, Blood Type: AB
* Guardian Chara: Temari
The former Q Chair (Queens Chair). Same age as Amu. When Amu rejected the offer to join the Guardians, Nadashiko tried many ways to convince Amu. She helps Amu bake sweets for Tadase as a birthday present for him. Her character after Chara Change is a battle hungry yakuza type who speaks in Hiroshima slang and carries a naginata.
It was revealed later on in the manga that Nadeshiko is a boy and his real name is Nagihiko. It is the rule of the Fujisaki family that the males are trained to become oyama (male actors who plays female parts in kabuki). That is why Nagihiko wears female clothes and goes by a female name.She is currently studying abroad in Europe.
In all, He is good friends with Amu, he looks over and supports Amu in her love life.
Kukai Souma
* Birthday: August 17, Blood Type: A
* Guardian Chara: Daichi
The former J Chair (Jacks Chair). He is one year senior to Amu. The captain of the Soccer Club, he is athletic and has good reflexes. Through the power of the Humpty Lock, Daichi managed a Chara Become once. Once, in the school magazine, he and Amu are mistaken to be a couple as a student got a picture of him holding Amu after she came out of her Character Change and lost her strength. He has Graduated, which is the reason he has been replaced. Saaya appears to have a crush on him, as when a school paper ran a rumour that he was in love with Amu, she was furious.
Yaya Yuiki

* Birthday: May 25, Blood Type: O
* Guardian Chara: Pepe-Chan
The girl serving as the A Chair (Ace Chair). One year junior to Amu. She likes the sweets baked by Nadeshiko. Her hair is tied in pigtails with a big ribbon. Her Chara Change character is a baby that uses a giant rattle as weapon, influenced by the "baby" character she has a crybaby personality. She doesn't know how to swim. Has a just born baby brother named Tsubasa. She is also a ballerina, though a rather clumsy one.
Ikuto Tsukiyoma
* Birthday: December 1, Blood Type: AB
* Guardian Chara: Yoru
A boy who wants Amu's Guardian Eggs. On Chara Change and Chara Become he grows cat ears and uses a claw-like glove. At first he is called "Nekomimi hentai cosplay otoko"(perverted cat ears cosplay guy) by Amu. He can play the violin. Like Amu, Ikuto too has sensitive ears. He possesses the "Dumpty Key". He is Utau's elder brother. He refers to Tadase as "Child King".
He signed a contract with Easter and is looking for the Embryo, an egg that will grant any wish. Its because of that he becomes an enemy to Amu, but privately he helps Amu in the shadows, a character whose true intentions are unclear.
Utau Hoshina (real name Utau Tsukiyomi)

* Birthday: November 9, Blood Type: A
* Guardian Chara: Iru, Eru
A 14-year-old junior high student idol. She sings in plays. Lunatic Charm is the name of Iru's Chara Become, during Chara Become and Chara Change Utau grows devil wings. The other Guardian Chara, Eru, is now with Amu in the place of Dia. The gentle Eru seems to be treated badly, Eru performed Chara Become with Amu and it surprised Utau.
She is actually Ikuto's sister, Utau Tsukiyomi. She has a brother complex and chases any woman near Ikuto and calls them "bugs". Whenever she enters Ikuto's sight, she disables her Chara Become and by all means trys to please her brother. At one time, through the power of the Humpty Lock, she did a Chara Become with Amu's Dia Guardian Egg, thus becoming Dark Jewel.
She is the vocals of the indie band "Black Diamonds" which is produced by her manager,Yukari Sanjou. She also has feelings for her brother and even forcefully kissed him once.Because she kissed him Ikuto thought Amu got mad, so he hugged her and asked if she wanted a kiss
Shugo Charas
Ran
The first to come out from Amu's Eggs. An athletic and honest character. Her hair is tied in a side pony tail. She has a pink sun visor, a red themed cheerleader outfit, and wears a heart shaped hair clip. Dislikes silence. During Chara Change, Amu gains increased athletic abilities. Little wings appear at her wrists and ankles, which allows her to jump high and fly. Having a straight forward personality, Ran made Amu confess her crush to Tadase on their first Chara Change.
Amu becomes "Amulet Heart" on Chara Become with Ran. The clover decoration of her Humpty Lock changes to the color pink. Amu dons a pink themed cheerleader costume in this form. Her special move is "Spiral Heart" which is executed with the Heart Rod. When Amu does Chara Change with Ran, Ran says "Hop, Step, Jump". Ran was seen on Peach-Pit's website before the publication of Shugo Chara! Volume 1.
Miki
A guardian chara with an artistic flair. A cool, quiet character. Her hairstyle is a short bob cut. She usually wears a pair of half-cut pants, a sky blue beret with a spade on it, and a blue themed outfit. Miki has shown an interest in both Tadase's Chara, Kiseki, and Ikuto's chara , Yoru. She comments that Yoru is cool and his tail is cute. This may imply the situation in Amu's heart.
The main ability after Chara Change is an increased artistic sense but that power is recklessly abused.
Amu becomes "Amulet Spade" on Chara Become with Miki. The clover decoration of her Humpty Lock changes to the color blue. Amu wears a white frilly blouse with a pair of hot pants, she also wears long, striped stockings and a garter belt; all in a blue themed costume. Her special move is "Colorful Canvas", where she paints with a giant paintbrush. Miki says "Drew, Draw, Drawn" during a Chara Change with Amu.
Suu
A guardian chara skilled in baking sweets and doing house work. A "my pace" character that is prone to silly mistakes. She has short hair with the sides grown long, curling inwards. She wears a bandanna on her head with a clover shaped hair clip and a green theme maid outfit. Dislikes caterpillars. Amu gains an improvement in cooking during Chara Change. Magical abilities like summoning large amounts of whip cream is also observed. In addition her speech and behavior becomes more lady-like.
Amu becomes "Amulet Clover" on Chara Become with Su. The clover decoration of her Humpty Lock changes to the color green. She wears a green themed balloon skirt maid costume. Her special skill is "Remake Honey", a restoration type skill. Su says "Chip, Syrup, Whip" during a Chara Change with Amu.
Dia (official name unknown)
Dia is Amu's fourth Shugo Chara, with a musical flair. She became an X-Egg, and then hatched as an X-Character in Chapter 17, after being discovered by Utau. Shortly after this, the character that emerged Became Character with Utau, forming 'Dark Jewel', and made a reappearance in Chapter 25 in a fight against Amulet Devil. Her special move with Utau was 'Shining Black', in which a dark light attacks the opponent. This Become Character has a defect, however, as Utau is not Dia's true owner; the Become Character dissolves quickly after it forms.
As Amu does not know Dia's real name, and still does not, as of Chapter 26, she just calls her 'Dia', a shorter form of 'Diamond'.
Dia became an X-Egg because of the change in surroundings, like Kukai graduating and Nadeshiko studying abroad. Usually X-Eggs form because of 'problems in the owner's heart', which shows that Amu has changed throughout the series from her inapproachable self to someone who socializes easily.
In Chapter 25, Amu convinces Dia that she can change, and so the 'X-Mark' was lifted, sparking Become Character, and making both the lock and key react. At the beginning of Chapter 26, Amulet Diamond was formed. Amu wears a futuristic outfit, in the style of an idol with lots of pleats, and pigtails, with a white headband. The Humpty Lock shines yellow.
Dia's true form differs from her X-Form - her true self is portrayed as a rather giddy and excited character, much like an idol may appear, whereas her X-Self was often seen as inapproachable. Her outfit changes from a 60s style dress, to a two piece with white boots. Her hair, which was at first portrayed as a 60s-style ponytail, became pigtails - both hairstyles included incredibly long hair, much unlike Amu's other characters. She has red-hair and orange-eyes.
Kiseki

Kiseki is Tadase's Guardian Chara. He looks like a mini Tadase with different-colored hair. He is extremely egotistical, loves to dominate but also has tsundere characteristics. He is always trying to outshine Yoru. His bearing is that of typical "king's fashion", complete with crown and mantle. Kiseki also occasionally calls meetings that require all the Guardian Charas to gather. In volume one, Miki seems to have a crush on him,saying he is cool. Likes to give orders but does not like to obey. Suffers from pollen allergy like Tadase.
Kiseki can do Chara Change with Tadase. When this happens, Tadase gains a golden crown and king’s scepter. The only reason he usually character changes is to help Tadase become confident and if Tadase is called ‘prince’.
After the "Black Diamonds" incident, he became able to Chara Become with Tadase. Tadase becomes "Platina Royale" on Chara Become and used the special skill "White Decoration", a skill thought to be a restoration skill.
Temari
Temari is Nadeshiko's seemingly elegant Chara. She is considered to be very girly and is always complaining about getting her kimono dirty, which always ends up annoying Daichi. Her hair tied in a ponytail with hair decoration in the shape of sakura flowers. She is skilled in handling the naginata and dislikes getting muddy.
Temari has the ability to perform Chara Change with Nadeshiko. Nadeshiko then becomes battle hungry, often over little things like getting hit with a ball. Temari herself seems to have an anger problem. Says "Chin, Ton, Shan" during Chara Change.
Pepe
Pepe is a baby-like Guardian Chara that belongs to Yaya. She always has a pacifier in her mouth, wears a full body baby outfit, and wears her hair in pigtails. When either she or Yaya get hurt or something goes wrong, both of them will begin to whine and cry in unison. Pepe could be described as a crybaby.
When she and Yaya perform Chara Change, Yaya receives a baby bib and a giant rattle that she uses to squash or hit opponents with. Says "pretty, cutey, love baby" during Chara Change.
Daichi
Kukai’s Guardian Character is Daichi. Daichi is very good at sports and can't seem to sit still. He was born when Kukai want to do many sports but had to choose. He wears a sweatband around his head, shorts, and a sporty T-shirt. When Daichi and Kukai do Character Change, Kukai becomes even more athletic and gains a star clip for his hair that looks like the same star on Daichi’s head band. Daichi was able to do Chara Become with Kukai once, resulting in "Sky Jack".
Yoru

Ikuto's Guardian Chara, Yoru, has cat-like features. He wears a pair of paw gloves and boots and dresses in punk fashion style. Yoru has a freedom loving stray cat image and often wanders around wherever he pleases without staying with Ikuto. Yoru loves to tease and annoy Kiseki, who in turn tries to do things only Yoru can do, like climb on buildings and railings. He also seems to be Scared of dogs.
When Yoru and Ikuto perform Chara Change, Ikuto grows cat ears and a tail. In Chara Become, Ikuto wears a spend-like outfit, has cat ears and a tail, and uses a glove with metal claws. In volume two, Miki seems to like Yoru as well as Kiseki. She, though, has more complements showing she has more of a crush on Yoru than Kiseki.
Iru (イル, Iru?)
Iru is Utau's first Guardian Chara. She has short, dark hair and devil wings, tail, and horns. She wears a two piece skirt and top that seem to come on as if they were bats. Mean, unkind and dislikes nagging. When she and Utau perform Chara Become, Utau sprouts bat wings and many wing shaped accessories. Her special move in "Lunatic Charm" form is "Nightmare Lorelei".In Chapter 25, Iru does a becoming character with Amu and becomes "Amulet Devil".
Eru
Eru is Utau’s second Guardian Chara. Has an angel appearance. She does not want to do Chara Become with Utau (her Chara Become with Amu is her first). Eru is gentle hearted and seemed to be treated badly. Eru left home and is now in the care of Amu. She uses english words like "wait" and "shut up" in her speech. Likes to nag, dislikes meaness and unkindness.
Eru performed Becoming Character with Amu once, resulting in "Amulet Angel", which surprised Utau. The clover decoration of her Humpty Lock changes to white colour. Her special move is "White Flag". As Amu is not the real owner as the Chara Become quickly dissolves after it forms.