If they realistically go with a DOA guest, I think they'll choose someone who isn't supernatural or powered in any way since Virtua Fighter is more a more realistic series and there's a major lack of any unrealistic elements besides the J6 organization's darker motives and Dural, even Kage is actually quite realistic as a ninja since its a legit style and I haven't seen anything too over the top from him that the other fighters can't pull off.
If they went that condition, I can see them using Kokoro(perfect as a style counter to Akira), Hitomi(Jean), Leifang(Pai), Helena(counter to Lion), or even someone like Eliot. If they did include a ninja, Ayane could be a likely choice since her style is more over the top moves over actual ninpo since she uses it far less than the other DOA ninjas, that or even Kasumi since only her teleports are used at times and even then she's using it to move at high speeds to get from point A to point B.
But then again, their collab with DOA5 was in 2012 up until 2017 when LR was done with support, so they really aren't obligated to give DOA a stepping stone. I think they'd more likely have someone from Tekken since their VF5US tekken pack was actually good with the costumes, it was just the lack of major support at that time since it was console only at the time