As far as I know, the following kinds of mixups exist in MBAA:
1) HIGH-LOW
Overheads (VAkiha 6C, C-Ciel BE4B, Akiha instant j2C)
Charge Overheads Cancellable to Lows (C-Arc BE5B/2A, F-Ciel BE4B/236A)
Jump Ins - faking the high, airbackdash jC at the last moment (a la C-Satsuki), blocked jC into IAD jC (VAkiha)
Fuzzy Guard (Len, C-Mech, F-Akiha under pit, F-Arc & C-Ciel with meter)
2) POKE-THROW
Poke-Normal Throw (Miyako; Len and VSion in corner)
While poke-normal throw is not a real mixup for the majority of the cast, some characters can combo after normal throw, making it a "real" mixup. 1A+D OS should be effective against this.
Poke-Command Throw (H-Koha, F-Kouma, C-Wlen)
3) CROSSUP
Crossup Mixup (C/H-Len & H-Sion dodge mixup, WLen teleport shenanigans, C-Hisui & H-Akiha j2C)
If not under the cover of something like WLen's BE236A, shield should be effective against this.
Sandoori (F-Satsuki, F-Kouma, I've seen F-Ryougi do it)
Of course all these mixups are more effective if they are in the cover of something like a summon or delay attack, in order to discourage backdashing, DPing, shielding, thus severely limiting your opponent's options and forcing them to react to the mixup. In the case of C-Koha, a Cactus setup or a Johnny mixup even gives more than one shot at 50/50.
The other way to make mixups more ambiguous is to hide them under something that obscures the vision. E.g. F-Aoko's Blue Fire mixup, Koha's mixup from molotovs and Wara under a Nero summon.
With all this in mind, what is the most effective type of mixup in this game?
Common sense leads me to believe it should be sandoori, as it not only gives many options (left, right, high, command throw), but also renders DPs unreliable, as inputting them the wrong way can lead to disaster.
P.S. Please correct me if I'm overlooking something.