Hello, Amanda,
What a great question! At Disney's Hollywood Studios, there isn't anything quite like the other child-centered activities found at the other parks, but I did immediately think of the
Jedi Training Academy. At the Jedi Training Academy, children have a chance to learn to be a Jedi and ultimately test those new skills against Darth Vader. It is a popular attraction; so if this is of interest to you, you will want to sign up immediately for it upon park opening.
I also think the Magic of Disney Animation is similar as guests have a chance to draw a Disney character under the guidance of a Disney animator. It's a great (and free!) souvenir!
And finally, there is the Honey, I Shrunk the Kids Movie Set Adventure where children can explore the backyard of Wayne Szalinski as if they were the size of the a bug.
I realize these aren't the same as the other activities you mentioned, but I think they have a similar feel for children getting to complete a fun Disney-centered task. If you have any further questions, please let us know.
Wishing you a magical trip! -
Kara