Setting:
This case takes place prior to the first case in AJ:AAttorney. The case will start from Gavin's POV as he follows a lead on the whereabouts of Trucy's father. It will lead him to the police station evidence locker, where he will find that the police station is hosting a school field trip. The lights flicker off, and a Gunshot is heard. The Judge is killed, and panic ensues, however, it is later discovered that the person was not the judge, but a impersonator.

Planned Evidence:
Attorney Badge
Autopsy Report
Letter
Collectible Stamp
Map of the Police Station
Photo of the Crime Scene (before the incident)
Photo of the Crime Scene (after the incident)
Photo of the Crime Scene (rear view)
Murder Weapon
Victim's Wallet

Setting:
Mr. Grossberg receives a mysterious call, and is found poisoned after going to Tres Bien. Evidence of blackmail surfaces, and Apollo vows to solve the mystery started in Case 1. Apollo changes his last name to Justice after this case.

Planned Evidence:
Attorney Badge
Autopsy Report
Coffee Cup
Security Camera Photo 1
Security Camera Photo 2
Security Camera Photo 3
Security Camera Log
Map of Tres Bien
Nail Polish
Bankruptcy Documents
Eviction Notice
Private Memo

Setting:
Unknown, takes place before Cases One and Two, Kristoph Gavin POV. A successful, and failed hit and run leaves Gavin's childhood friend maimed, and one dead. Hours after the accident, the police file charges on Gavin's friend.
Planned Evidence:
Nail Polish

Setting:
Unknown, takes place after Case Three, shows Gavin's reason for turning evil.
Planned Evidence:
Attorney's Badge
Nail Polish

Setting:
Takes place during the MASON SYSTEM case. Everything unravels as Apollo realizes that the case he thought closed years ago is not so.

Case 1: Gavin was the one who actually fired the shot, although the case will end inconclusive. The impersonator was actually an investigator looking for leads on the truth in the case that lead to the end of Phoenix Wright's career, as not all disbelieved Wright's claims of foul play.

Case 2: The case will be similar to the Ron DeLite case in terms of general plot, but will not be filler. Also, a new chef will be in charge of Tres Bien. The new chef will die by the end of the case.

Case 3: The nail polish is given to Gavin's friend after the end of the case. In between Case 3 and Case 4, the lawyer sends a letter between Case 3 and 4 telling Gavin to destroy the nail polish as the gift was mixed up with a evidence for another case. The letter never reaches Gavin in time due to a name typo.

Case 4: The lawyer who defended Gavin's friend will be revealed to have done it because their sister was the one who did the hit and run, and offered to consul them pro bono because of a guilty conscience. The case is a result of an unfortunate mix-up, the nail polish was not the one originally meant to be given, rather was mixed with a evidence sample in a different case. Gavin's friend dies from the poison in the polish, and Gavin becomes disillusioned in lawyering for truth. Gavin's brother is the one who reveals the reason the lawyer who defended them in case 3 did it, at the end of the case. Planned irony being the lawyer is a distant relative of Trucy/Apollo.

Case 4 is told by Gavin, in a similar manner to how MASON worked, except it takes place years after MASON, sort of a reflection by Gavin. He will explain that he now know the polish was not meant to have been given, after finally receiving the letter of apology that never until now reached him.

Case 5: This case will reveal what actually happened in Case 1.

So the order timelinewise is 3, 4, 1, 2, 5?

1/2/5 will be from Apollo's POV,
3/4 will be from Kristoph's (might make it like the MASON system, not sure), I'm deciding if it should be like a reflection written by Gavin in jail.
Therefore, its mainly focused around Apollo.

But it seemed like Kristoph did most of it in the first case, from what I've heard.
Plus, I'm not a fan at all of someone suddenly taking the main character's game like in 4-4.