Hi there, long time TAS viewer, first time poster.
I think the real nightmare in trying to pull off a TAS of this game is going to be optimizing the randomized dungeons. First you have to make the decision of wether or not you want to obtain an item, recruit a specific pokemon, or simply get off the current floor.
Then you've gotta luck manipulate the floor into making the task quicker (IE: Putting your goal right next to you.), which is the most difficult part. After doing some tests, I'm lead to believe that the entire dungeon is generated as you enter the first floor. I think you may need to have some very extensive knowledge of memory reading and knowing what values generate what parts of the floor before you can even begin to optimize the dungeons themselves.
Of course, you also have to make the decision wether to spend your time fighting and leveling, and since you have to fight bosses eventually, and your partner is as smart as a brick (And if they die the mission ends as if you died). Luck manipulation can take you far, but you have to take the partner's actions into consideration, as well, as they don't run from enemies, even if you do.
I'd love to shake the hand of the person who could pull off an optimized Mystery Dungeon TAS. I think it may be quite a while before we start seeing some nice attempts at it, though, due to the havily randomized nature of the game's dungeons.
There are some guides on GameFAQs that have item drop locations/rates, pokemon locations, etc. So if you realy wanted to (and had the in-game memory knowledge) you could pull this off. It would take a lot of hard work and dedication, though.