For the konami code you have to go up, up, down, down, left, right, left, right in the blue forest (you can also follow the fireflies)
for sunny's third scene you have to do the konami code and talk to the witch with sunny in your team
for fluffy's third scene you have to collect DO! art n.16 and then talk to fluffy
Try using blinky's ability if you don't find something it's very helpfull and it gives you some tips on how to find all secrets of the game