Go to the blackboard in the clubhouse and press A, after the message has been read press L, R, A then B to get the hidden picture
In Hamstarr Manor, go to the place where Mean Oxnard is and go to the back of the room. There will be 3 ghost hamsters. Go to the middle one and talk to him. Then press B, L, A, B, A, and R. You'll be sure to get the "Too Much Good Stuff" picture.
And in Rainbow Land, Go to where Bo is, and you will see a poster of Bo, and the border is green. Press A, and Hamtaro will say, "Heke. It's a poster of Bo." And press "L, A, L, B, A, B, R, and R. And you be sure to get the "Rainbow Riders" picture.
Okay! I'm so glad I found this! I just got it a minute ago, when I was really frustrated.
In Clover Elementary, Go to the game that Cappy plays. "Crazy Cap Catch". Go to thehamster that throws the hats, but don't talk to him. Go all the way right, and through the window. You might find a seed. Go all the way to the left, and you will see a Shogun Wig. Press A, and Hamtaro will say "It's a Shogun Wig." (Notice that the hidden pictures startes with "It's") Then press L, A, B, L, and R. And you will get the "Does She Know?" picture.