I don't know if this is even possible to find dlc models ? I was on a forum where they posted all raw models, but they only had data from the disc, so no dlc. So can you guys do ti ? It would be really great.
I think you should try the campaign data, The official DLc pages says you need the "latest campaign pack" to be used, So they might not be in the actual DLC files to begin with. I'm trying to get my hand on the campaign packs as well. If it helps, the Campaign Packs include unlock-able costumes, taunts, etc when playing Campaign mode, when it comes to the DLCs, you can fight them(provided you have the latest data installed) but not play them unless you fork over the money.
Damn, having the campaign pack 2 would be really great, we could extract so much models !
I have no clue how to get those datas, so I can only wish you luck unfortunatly =/ And hope you get your hands on it.
I found a place where to download the DLC: isogames-download.net/2014/04/jojos-bizarre-adventure-all-star-battle-dlc-ps3-eur-mega-firedrive/
And I managed to unpack them, but not all of them were included, try to find a link with more DLCs!