I'm not fan of Shugo Chara or seen that show. But I read manga with my friend, I think it's a okay anime. Then I play the opening song from Shugo Chara. Suddenly I thought of Lauren Faust with ponies for no reason.
In Shugo Chara, a person can combine with one of their Charas (what the ponies are representing here) and perform a Chara Nari (or Character Transformation), which is actually the main reason to have Shugo Chara as a Mahou Shoujo. Check this out: [link]