There are 5 hidden tasks located in Genesis, under the tab Classified. They will only appear once you've completed them. All items must be pinged in a single trial, your progress will not be carried over.
This guide will cover only the solutions to Duck Hunt, Inspector Don and Let's Fla-mingle.
Solutions for This Flock Can't Run and The Devil's Checkmate will be linked below.


For Duck Hunt:
There are 10 ducks scattered throughout the trial Poison the Medicine, you'll have to ping them all to complete this task.
Your reward for completing this task will be a small sized trophy you can display in your sleep room.


For Inspector Don:
There are 7 post it notes scattered throughout the MK challenge Kidnap the Mistress, 5 above ground and 2 in the sewers. You'll have to ping them all to complete the task.
Your reward for completing this task will be a medium sized trophy you can display in your sleep room.


For Let's Fla-mingle:
There are 10 flamingos scattered throughout the trial Liquidate the Union, you'll have to ping them all to complete this task.
Your reward for completing this task will be a medium sized trophy you can display in your sleep room.


For This Flock Can't Run:
You can follow this guide by JTTopCat.
There are 10 seagulls scattered throughout the trial Pleasure the Prosecutor, you'll have to ping them all to complete this task.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3420196995
Your reward for completing this task will be a new ESOP cosmetic.


For The Devil's Checkmate:
You can follow this guide.
There's an easter egg located in Disrupt the Neighbourhood, you'll have to input the code to complete this task.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3565809256
Your reward for completing this task will be a new chessboard design for your sleep room.

The ducks usually spawn in pairs with the exception of Duck Brown and Duck Norris.
There are 10 ducks to be found in total around Poison the Medicine.
Upon accomplishment of this task, you will receive a small sized trophy you can display in your sleep room cell.

1. Entrance area
   [Donald and Duck It]
   
   Under the bridge, you'll find Donald and Duck It in the water
   Facing the rest of the trial, Duck It is on the left, near a boat
   
   Donald is on the right, under the pier
   
   
   
2. In front of Laboratory Chem Co
   [Seductive and Duckr. Codereview]
   
   Under the stairs, you'll find Seductive and Duckr. Codereview
   Facing the entrance to Laboratory Chem Co,
   Seductive is on the left side, floating near a barrel
   
   Duckr. Codereview is on the right side, hidden beneath the staircase
   
   
   
3. Inside Laboratory Chem Co
   [Duck Brown]
   
   In the male toilet, floating in the toilet bowl, you'll find Duck Brown
   
   
   
4. In front of the boat
   [Ludwig Von Duck and Tape]
   
   Go behind this metal fence, you'll see a small wooden outcrop with barbed wire around it.
   Behind the barbed wire fence, you'll find Ludwig Von Duck and Tape floating in the canal.
   Ludwig Von Duck is behind the left side of the fence
   
   Tape is behind the right side of the fence
   
   
   
5. Along the cart track, near where the drugs are stored
   [Duck Norris]
   
   Go down the stairs, to the back of the area where a sewer pipe is visible, you'll find Duck Norris
   
   
   
6. At the back of the boat, near the chemical storage area
   [Tales and Duckr. Pepper]
   
   Floating in the canal, you'll find Tales and Duckr. Pepper
   Tales will be on the left side of the boat
   
   To find Duckr. Pepper, you'll have to go to the stairs leading down to the side door of chemical storage to spot it
   

There are 7 post its scattered throughout Kidnap the Mistress, with 5 above ground and 2 in the sewers. Each post it gives a clue as to where the next one is located.
Upon accomplishment of this task, you will receive a medium sized trophy you can display in your sleep room cell.


Ground Floor Spawns

1. Control Room, 1st floor
   
   On the main table
   
   
   
2. Irish Pub, 1st floor
   
   
   Behind the cash register on the counter
   
   
   
3. Garage, 1st floor
   
   On this shelf in the middle of the garage
   
   
   
   
4. Fire Station, 2nd floor
   
   Behind the basketball hoop at the back of the room
   
   
   
   
5. Motel, Room 203, 2nd floor
   
   
   Behind the blue couch in the back of the room
   
   

Sewers Spawns

1. Sewers, Speakeasy/ Bar
   
   
   On the side of the jukebox in the back of the room, behind the mannequin
   
   
   
2. Sewers, Old Subway
   
   In the last train car, behind the last bench
   
   

There are 10 flamingos scattered throughout the trial Liquidate the Union. Ping them all and upon accomplishment of this task, you will receive a medium sized trophy you can display in your sleep room cell.

1. At the start of the map, behind the fence near the red car, you'll find Diego
   
   
   
   
   
2. Near the gathering point of the map, behind the rioters, inside the flaming car, you'll find Flambé
   
   
   
   
3. Inside the mansion, in the pump room of the swimming pool area, you'll find
   Pink Flaming-oyd
   
   
   
   
   
4. Inside the mansion, in the game room, you'll find Phoenicopteridae in the rafters
   
   
   
   
5. Outside the mansion, along the rails, you'll find Don and
   
6. Featherstone beside a hedge
   
   
   
   
7. In this house beside the previous 2 flamingos, beside the piano, behind a guitar you'll find Flamenco
   
   
   
   
8. At the final checkpoint area, along the rails, go into the room behind this fallen mailbox, through the crawlspace in the next room and you'll find Fly-mingo on the ceiling
   
   
   
   
   
9. Also in this area, through the coop door, go up the stairs and onto the balcony. On the opposite balcony, you'll find Flamboyant.
   
   
   
   
   
   
10. At the finale, in the cold room, on one of the shelves, you'll find Flamingo Starr
    
    
    

Special thanks to Prett for identifying the post it task in the first place, and Therapist, NocRys, Imp, 关山, Riccio and Lito for going through the maps and finding the items with me.
Let me know if I need to add or change anything.
Thank you for reading and please give a rating/ award or comment if this guide has helped you!^^