I've been looking into fanmade Ace Attorney casemakers, because God knows I think writing these things is, if possible, even more fun than playing them. The AA wikia has a decent list of the computer-based ones -- I was about to say "PC-based", but at least two of them seem properly mutli-platform: The Ace Attorney Online casemaker professes to work on any platform that supports a full Firefox installation, and PyWright should work on any platform that supports a Python interpreter.

(They also miss one that's specifically for use on DS flashcards that support homebrew software, Ace Attorney DS. I have an R4 -- never you mind what they're usually used for, they are fantastically handy if you are easily bored on public transit and need to play Day Of The Tentacle on your way to Quincy -- and while the program is an obviously amateur work and can be a skosh touchy about things like 'being the first app run after bootup', it does do what it claims to, and the scripting language is considerably simpler than the PWLib variant of the Anime Image Game Engine builder.)

They all have advantages and disadvantages, but so far PWLib looks like the most complete, even if it isn't the absolute most human-readable thing I've ever run into. (That title goes to a text-adventure building kit for the Z-machine called Inform 7. Remind me to ramble about that sometime. It's phenomenal.) Most of the engines support most of the features of the first three Phoenix Wright games, and with some creative scripting looks like they would also probably handle the "Logic Chess" dialogue mechanic of Edgeworth's second game, although I'm unsure if you could get all of them to approximate the draggable facts in AAI1's "Logic", Kay Faraday's "Little Thief" gadget, or Apollo Justice's zoomable "Bracelet" examinations in court. PWLib supports Psych-Locks mechanically, including video-inverting the background, although it lacks the proper chains animation.

The difference in sprite style in dialogue sequences between AA and AAI is unimportant; the display function that handles speaking sprites and animation will happily draw anything you want under the text box, to a maximum size of 256 x 192px, which is the resolution of a DS screen. Code-wise, "Deduce" is probably doable, although likely as a variation of the "Examine" first-person crosshairs, as I haven't seen any indication that any of them support the AAI walking sprites. "Argument" is just "Testimony" with a different name.

One thing PWLib supports that some of the others do not is a very fine control of the text speed in the dialogue boxes. A lot of crime-things, especially the American- and European-developed ones, are of a style generally referred to as "point-and-click adventure". Another good example is The Secret of Monkey Island. The gist of it is, that you control a character who wanders around picking up items and using said items on other items until, sometimes accidentally, some combination solves a puzzle, allowing the player to continue. There are dialogue snippets in these, sometimes a lot of them, but the function of most of them is to provide atmosphere, and to alert the player (usually through changing) that they've had some sort of effect on the game world. The AA/AAI series is of a genre referred to in Japan as "visual novel" -- the oft-mocked dating sims are a subset of the same category of games. They're exceptionally dialogue-heavy, the exact content of the dialogue matters a lot, and it's usually only through paying attention to it that you can figure out what branch of the script tree you're on, and how to change it. It's a lot of significant text with cute animations, essentially. The AA series is also not blessed/cursed with an overabundance of voice acting, so the ability to change the speed (and color, and format) at which text appears makes the difference between Wendy Oldbag rambling obstructively about her youth and her crush on Edgeworth, and Phoenix speaking slowly and distinctly in order to make a point about a contradiction in court.

It's subtle sometimes -- less obvious than the Japanese habit of using unaccompanied punctuation like "...!" or "?" in speech bubbles to indicate marked but wordless reactions -- and shouldn't be all that hard to code, but many people miss the significance. Writing courses talk about pacing in the script, but not often pacing of the text itself; that seems to be confined to discussions of concrete poetry forms, which can be an effective cure for insomnia when delivered by a less passionate and entertaining personage than Stephen Fry. It's an issue unique to motion-based art forms like film and video games.