Oliver was going to be in an OCT that never came about; therefore has no story, the Big Guy (whose name escapes me) is from a much older story that Endling gave up on or something, and Ree is from Ree.
The finales are the Endzone finales. Endzone was an OCT Endling hosted that took place in the Everafter asylum. It is not canon to EverAfter. The finale is the long, long, long, long awaited conclusion of Endzone.