Unused Content are things that didn't made it to the final game. Most of the unused content is the beta content as most of the beta content didn't made it to the final game.
Chuck (Beta 1.0.4)
Chuck's behavior in Beta 1.0.4 was a bit different as the player will only back away Chuck using the Piggy Ham Bacon Head rather than using the flashlight.
Suit-1 and Suit-2
Suit-1 and Suit-2 were unused enemies that never made it to the final game. As said by the creator, Suit-1 and Suit-2 were scrapped from the final because they were too difficult to make and were only easier to make when they're drawn into sketches.
Suit-1's Chains Tightener and the Generator Charger
These unused mechanics from Beta 1.0.1 was both used in the same way. The two mechanics was used like the Music Box from Five Nights at Freddy's 2. This was removed because of possible copyright.
The Addict and The Generator Room
These were locations were places that holds the Suit-1's chains tightener and the Generator Charger. The Addict holds the Suit-1's Chain Tightener mechanic and the Generator Room holds the Generator Charger mechanic.
This was an umimplemented idea from Beta 1.0.4 made by the creator. It was supposed to be an easter egg that effects the plot of the first game. There was a total of 5 piglets. One would be found in the Hallway lying down on the floor in a blood pool. The second one would be seen in the dark in the Show Stage (FNaP). The third piglet would be seen hiding in Lucky's Cave. The fourth piglet would then be found in the TV static, which was replaced by the Piggy Ham Bacon static. The final and fifth one almost made it into the game as a poster saying "HELP ME" until the remake of the new office.