Idtipsa/guide

Dancer
Enter the Blue Flower World. Go right a bit and up from the door. Find a large area of blue flowers with an outfit hanging from a stand. Interact with the stand.

Chains
Enter the Blue Flower World. Go down and left from the door and step into the center of a large circle. Go right and up and enter the building. Enter the door on the far left. Interact with the NPC. Go left. Go north-west and interact with the peg in the ground.

Cheerleader
Enter the Blue Flower World. Go down and left from the door and step into the center of a large circle. Go right and up and enter the building. Go up to the fourth floor to a giant room with NPCs. Go to the top-right corner of the room and enter the door. Enter the circle of cheerleaders and interact with the girl in the middle of them.

Suit
Enter the Blue Flower World. Go down and left from the door and step into the center of a large circle. Go right and up and enter the building. Enter the door on the far left. Interact with the NPC.Go left until you a monochrome head under you and interact with it.

Go through the doorways on the building above you until you're teleported to a city filled with NPCs. Interact with the puff of smoke beside the woman.

Fairy
(Requires the Cheerleader Effect.) Enter Onion World. Go northwest until you see a black line. Use the Cheerleader Effect to open the pathway. Head north and west until you reach the top of the area: there, you'll find a entrance in the wall. Use the Cheerleader Effect on the NPC blocking your way. You'll be treated to a bit of UFO cruising next; wait a little while before hitting Z to proceed. Exit down to the room with the heads, then carry on right. You'll eventually reach a maze. Navigate the maze (beware of chasers) to reach the white butterfly. Interact with it several times until you reach a messed up version of Fairies Place (Fairy's Eve)--you'll know you're there when you hear warped music begin to play. Hitting the Z key will switch between sped up and slowed down versions of the BGM. Search for the the right combination of music speed and entrance so that it warps you to another house rather than sending you to the field. Carry on in this way while switching between music speeds--it might take a while to figure out, but eventually you'll arrive inside Iris's Room. Interact with the sparkles as Nex to get the effect.

Flower
(Requires the Cheerleader and Fairy Effects.) Enter Onion World. Go northwest until you see a black line. Use the Cheerleader Effect to open the pathway. Go up then immediately left through the doorway at the end of the way. You'll be inside a hallway. Equip the Fairy Effect and make your way up. Interact with the flower in the center of the next room to get the effect.

Mushroom
(Requires the Dancer Effect.) Enter Onion World. Head northeast until you see two screws near some swirls. Go between them and using the Dancer Effect dodge the chaser and interact with the crossed arrows sign. Head north until you hit two black arrows facing opposite ways. Interact with it, then head west and a bit south. Interact with the short arrow-headed NPC moving in a diamond pattern. You should find yourself in a swamp.Go south between two purple flowers. Head north in the next area and enter the opening in the wall. Once inside, go up the winding pathway, then take a left when the path forks. Continue going upwards while turning as little as possible. In the next area, continue left and up, then right and up. Once outside, interact with the small mushroom on the ground to get the effect.

BG
Enter Onion World. Head east and south until you reach an onion with a bleeding eye and a red circle in its center. Interact with it to get the effect.