I think it might be forward and meter button. Not 100% sure on this though.
Forward and meter is interesting. You have to commit to not blocking and if there is some sort of recovery after doing it, the offensive player could bait out and punish a missed push block for full combo.
Of course if the game is similar to SF, then you will stay in block stun regardless if you let go of block to do a push block, or churn some butter for a mashed SRK or piledriver, so nevermind, then.