You've got it all worked out already, haven't you?
p.s. In your defense, I sometimes get really excited thinking about stuff like this too. Yeah, they probably will never manifest: but it is cool to imagine and a really exciting moment if/when it does come out the way you anticipated
In terms of a moveset for him, I'm thinking of this for his specials:
Neutral Special: Objection
Side Special: Present Evidence
Up Special: Ladder v Stepladder
Down Special: Collect Evidence
Final Smash: Penalty/Ace Attorney
Objection is pretty self explanatory. The Evidence system can function is it did in Marvel vs Capcom 3, but without modes you can switch between. Instead, you can collect up to five pieces of evidence, and present them to deal damage. Evidence can also have an effect on his Final Smash, more on that later. In Ladder vs Stepladder, he can press the button to create a step ladder, and hold it to create a ladder. The ladder covers more height and is better for recoveries. And now onto the Final Smash. If Phoenix Wright doesn't have 5 pieces of evidence, he will activate the final Smash "Penalty" in which he presents a piece of evidence to trap the opponent, and then the judge slams his gavel saying "Penalty" Both players will be hit, but only the other one will receive damage. For "Ace Attorney", a laser will fire across the screen, and anyone hit in it will be subject to the final Smash. The camera will zoom into Phoenix's face, and then he will have a realization and the "correct option" will shatter, dealing damage to the opponent. After which he will Object, and then it moves to a courtroom. Phoenix, Apollo, Athena, Mia, Edgeworth, and Naruhodō will all yell "Take That!" at the same time, dealing extreme damage to the opponent