The memory bonnie plush can be found in Bonk a' Bon: Bonus Round. aka Bonk a' Bon 2.
You want to play the game normally until round 4, in round 4 a tiny glitchtrap will appear in one of the holes, when it does you want to hit it, breaking the machine, then instead of following the code you want to do the code backwards, for example if it was 1 2 3 4 you would want to do 4 3 2 1.
After that a hand should reach out giving you the memory bonnie plush.

The memory chica plush can be found in Fazbear Theater.
When you spawn in you can find a trashcan to your left, put the following items in.

Chica lemon bar.
Chica chowda.
Chica drink.
Chica blended drink.
Once all 4 items has been thrown into the trashcan a hand should reach out from it, giving you the memory chica plush.

The memory golden freddy plush can be found in Fizzy Faz Night 3.
Spawning in, you want to wait for the cup to appear, once you have the cup, you want to hit the red lockdown button to your right, then once your in lockdown grab the sodaroni can over by the machine and pour it in the cup, should give you one bar, then after that fill the cup in this order.
Chicken.
Lemon.
Coffee.
Candy.
Then once you have all 5 ingredients in the cup put it in the machine and press the button, after that a hand should appear and give you the memory golden freddy plush.
(Keep in mind that you have to fill and serve all within the lockdown time or it won't work)

The memory puppet plush can be found in the Office: Puppet Master.
When you spawn in, there should be a draw to your left with a keypad inside, open it and put in 1983.
Doing so will give you the memory puppet plush.
It's possible to acquire the tiger rock plush in the same game.

However.. if for some reason it's still locked for you like for me, you can angle your head to see the keypad inside and input the code, might be a bit tricky to input the code correctly first time so make sure to close the doors to buy yourself more time.

The memory freddy plush can be found in Fazerblast: FNAF 3.
First of all to unlock this level you must shoot the 3 rockets in the following levels.

Fazerblast 1.
Fazerblast: Western.
Fazerblast: FNAF 1.


After you have shot all 3 rockets go to Fazerblast: FNAF 2 and beat it with at least 7000 points.
To do so you want to wind the music box.
Check CAM 05 for withered bonnie and balloon boy.
CAM 06 for toy bunny, toy chica and mangle.
CAM 08 for withered foxy.
CAM 10 for toy freddy.
To take care of the vents you want to laser blast the button over the vent to the left or right and shoot the balloons of the animatronic.

















For toy freddy you simply want to laser blast the button next to the mask as soon as you can.










For the puppet you want to prevent the music box from winding all the way down, to do so simply laser blast the button from time to time.











For withered foxy you want to laser blast the button in the middle of the office and throw balls at him.

Note: Hovering in the cam the animatronic is in will close the camera faster (from my experience) giving you a bigger window to react.

If all done correctly will trigger an event and grant access to Fazerblast: FNAF 3. Now all you have to do is just beat it and you should get the plush.

The memory foxy plush can be found in Capt Foxy's Log Ride.
To get this plush you must hit all 3 helpy cutouts and all 4 decagrams, screenshots of their locations below.

Helpy and decagram 1.















Helpy and decagram 2.
















Helpy and decagram 3.
















decagram 4.

The tiger rock plush can be found in the Office: Puppet Master.
When you spawn in, there should be a draw to your left with a keypad inside, open it and put in 1979.
Doing so will give you the tiger rock plush.

It's possible to acquire the memory puppet plush in the same game.

Thanks for reading and I hope you found this helpful, if you have any questions feel free to ask.