Who is that blonde kid from shugo chara doki?

By blonde kid i think you mean Tadase.

Spoiler alert!

Tadase Hotori(辺里唯世 Hotori Tadase) is a main character of Shugo Chara!. He is the leader of the Guardians, also known as the "King's Chair". He is in the same year as Amu Hinamori, and is another main character of the series. His dream is to be the king of the world. Though he may say this, Kiseki was actually born by Tadase's dream to have a strong-willed heart, much like his grandmother when she was still healthy. He only wants to protect the ones he loves.