This is a list of Doa3.1 true combos. Note that all moves with a ( ) in a string are the true combos. :kasumi P 2 in 1 on normal blow and counter blow PP 4 in 1 on normal blow PP 3 in 1 on normal blow P(K:K) 2 in 1 on normal blow P:P 2 in 1 on crouching opponent P:K 2 in 1 on crouching opponent :3bK 2 in 1 on crouching opponent :hayabusa P 2 in 1 on normal blow and counter blow P(P) 2 in 1 on Counter/high counter blow PP 3 in 1 on crouching opponent :hitomi P 2 in 1 on normal blow and counter blow P(6:P) Non holdable P(K) 2 in 1 on all blow types P(:2bK) 2 in 1 on normal blow P:P 2 in 1 on normal blow K:K 2 in 1 on normal blow :zack P 2 in 1 on normal blow and counter blow :3bP 2 in 1 on crouching opponent K:K(K) 2 in 1 on normal blow :2bK(K) 2 in 1 on normal blow K2b:k(K) 2 in 1 on normal blow :genfu P 2 in 1 on normal blow and counter blow PP 2 in 1 on normal blow +:K(P) 2 in 1 on all blow types :brad P 2 in 1 on normal blow and counter blow P:P 2 in 1 on (high)Counter blow :tina P 2 in 1 on normal blow and counter blow 6P 2 in 1 on crouching opponent 6:p(P) 2 in 1 on crouching opponent 6:P(K) 2 in 1 on crouching opponent :3bP 2 in 1 on crouching opponent :bass P 2 in 1 on normal blow and counter blow P:P 2 in 1 on counter blow(within closed stance) P:P 2 in 1 on normal blow :leon P 2 in 1 on normal blow and counter blow 6:P 2 in 1 on normal blow PP 3 in 1 on normal blow P:P 2 in 1 on normal blow PK:P 2 in 1 on normal blow :bayman P 2 in 1 on normal blow and counter blow P:P 2 in 1 on normal blow :k(P) 2 in 1 k 2 in 1 :jann P 2 in 1 on normal blow and counter blow P:P 3 in 1 on normal blow :lei P 2 in 1 on normal blow and counter blow 3:P 2 in 1 on normal blow and counter blow :christie P 2 in 1 on normal blow and counter blow P:P 2 in 1 on normal blow P:K 2 in 1 on normal and counter blow :helena P 2 in 1 on normal blow and counter blow P:K 2 in 1 on (high)Counter blow (within closed stance) P:P 2 in 1 on crouching opponent P:K 2 in 1 on crouching opponent :hayate P 2 in 1 on normal blow and counter blow P:P 2 in 1 on all blow types P:P 2 in 1 :ayane P 2 in 1 on normal blow and counter blow +P 2 in 1 on normal blow :ein P 2 in 1 on normal blow and counter blow P:P 2 in 1 on normal blow
I think :genfu has p:p as a 3i1 on crouching opponents as well. Also, any combos with a ( ) around some attacks are what the #i1s refer to.
there are a lot more true combos and un-holdables in doa3.1. these are the ones I found without the help of another player.