Dang, I can't believe I forgot Ema Skye. I'm going to add her in later.
Also, I've decided to make 2 spirits legendary because it's honestly really hard to give all these spirits an accurate rarity rating. Most of these characters are very important in Ace Attorney (maybe not Winston Payne, he's mostly the tutorial-like character). But yeah, you're right, all the DLC boards only came with 1 legendary spirit, and all of them are support spirits.
Now that we're on the topic of the DLC Spirit Board, I've also thought of the theme they could use while you're selecting a spirit. I think using one of the "Court Begins" themes would make perfect sense. They could use the one from the first because it's more iconic, but I'd prefer if they used the one from the second or third game. I think the 2 songs fit much better for some reason, but I can't really describe how.