There are lots of street food in Takeshita street.
For instance, crepe in Takeshita street is very famous and popular. You can find this Japanese style crepes in other parts of Japan, too but I feel crepes in Harajuku has a lot of whip cream and fruits inside comparing to those in other cities!
Also, a huge cotton candy from TOTTI CANDY FACTORY is famous. You'll be surprised at its size! Also, fresh fried potato snack Jagariko at Calbee+ is a must try.