The theories I have so far
Kachousen (her fan toss which is qcf+P on the KOF series) is going to be used as a long range projectile as it normally is. It would be very linear and yet it can also be utilized to keep opponents from whiffing moves at longer distances. The notation in this scenario would probably be 236+P.
Mai's CD attack from KOF98 may end up being her CB. Her Power Blow is more than likely going to be a variant of Shinobi no Mai from KOFXIII or something a bit more elaborate to fit DOA5LR inner workings.
She also gained a target combo in KOFXIII (st.B, st.D). In KOFXIV, she retains this target combo, except it actually cancels into special moves. Several of her moves and strings may also end up being cancelled into her special moves. Musasabi no Mai has two variants: One that is used on the ground as a charge input and the other which is used in midair, which is a nose dive. This will more than like manifest as a move that allows her to distance herself or close the gap between herself and the opponent. Musasabi no Mai on the ground is done with down~charge~up+P (pressing up in a specific direction will cause her to travel forward or backwards. She will travel backwards by default if the player just simply presses up). If the player holds the punch notation while she touches a nearby wall, she automatically performs the air version of her Musasabi. There is also a chance that her special moves from KOF might end up requiring P+K or K+H inputs while singular command moves and strings end up being associated with P and K inputs.
I just hope that Mai does not suffer the Tekken 7 Gouki syndrome, where she ends up too strong, despite the 2D to 3D transition. Because, I can already see some potential dangers of this characters based on my experience in playing her in her respective series. Musasabi no Mai (ground version) may end up being too powerful of an escape option because she moves so quickly and so far away. I also wonder if chip damage would become a thing in DOA on behalf of this character. I also wonder if Mai is going to have her own meter system where she can temporarily free cancel her moves like the HD/BC combos in KOFXIII/02UM or based on how KOFXIV works. Hell, there is a likely chance that she may end up having more than one PB because the PB seems to be the equivalent of a "super" move in a way.