There is a mind game at about 2 crouchdash distances away or a dash into 2 consecutive crouchdash distance. If you commit to an electric on the 2nd one it can control space to some extent but moves like Lee's b4 or 44 or Bryan's neutral orbital when done in reaction/anticipation to your movement will clip you out of it, If the opponent is like let's say playing Jack and he tries to stick out fF1 to challenge that space he is getting blown up and he'll lose the trade, most likely.
Personally, what I do is a short sidewalk left into standing block after I see that the Mishima player is almost at a crouchdash distance away (roughly slightly inside lets say Bryan's b1 range). When timed correctly, everything done on the 2nd crouch dash or 2nd crouchdash into f4 or fF3 will whiff or get blocked. Hellsweep is going to whiff and with Kazuya the punch portion of the HS will land on block and leave him at -15.
As a Mishima, If you see someone do this, there is a way to throw off their timing and commit to an electric on the 3rd consecutive crouchdash when you are already in their face. Needless to say this does not control space in any way what so ever and if they challenge your movement with anything before that, you will get hit. However, you have a chance of hitting them as they are sidewalking with the electric. However you must watch out for the sidestep crouch blockers, particularly as Devil Jin.
Dash electric or deep dash electric can't be sidestepped on reaction to the dash when at neutral. Lateral movement between range 0 and this tip range is asking to get EWGF'd. Either stay outside this range or point blank range, don't get stuck in the middle. If you are inside this range and you don't know "whose turn is it" because neither player retaliated after block/hitstun, it's not your turn. You will get EWGF'd once again if you think you can commit.
One thing I like to do with Heihachi to test someone I've never fought before is to maneuver myself into about dash - crouchdash - fF2 range( all of the 3 cancelled into each other in quick succession), or rather, just outside maximum effective range for Heihachi. I'll commit to the fF2 at some point like this. If it's 5 bars and the opponent gets hit, their movement is not very good or their understanding of neutral is somewhat underdeveloped yet... or they just haven't played against Heihachi. If the opponent blocks and maybe punishes they are OK, maybe more rushdown oriented and just looking to play safe. If the opponent sidesteps left to evade the fF2 and launch me they have good movement and they have experience fighting Heihachi.
Only real way to stop the wavedash into 50/50 at neutral is to contest the space with something every now and then and risk eating the electric. Quality high crush moves are vital, otherwise the only "safish" option you are stuck with is "random" standing 4 and hoping the Mishima gets CH'd out of the electric. Chucking out advancing launchers is also not a bad idea every now and then. Just because someone can wavedash into electric doesn't mean they know how to use it or have any control doing it. Being intimidated to do anything is a sure way to lose.
With Heihachi having yolo ws1, f3 and fF2, he has the best space control of all the Mishimas. Dash into crouchdash into ws1 is unsafe but I've found it is one of the highest priority things to do with the beefiest hitbox, the chance to mash anything out and beat Heihachi out of it or try to evade it is very slim. Random ducking is not an option against Heihachi, but then again his 50/50 is ass so there is no real reason to duck. Devil Jin faces the problem of being steppable even right into crouch due to his lack of a safe homing mid and df1 being linear. F1+2 is ass and bf2-series is unsafe too so you might as well chuck out the iWS2 if you are going to put yourself at -12. Learning how to wavedash into iWS2 with DVJ is of critical importance to curb the "sidewalk into duck" option selecting. The new fF4 Changes a lot of things for Kazuya, I forgot how big of a game changer it is until I actually got my hands on the game. I remember being super stoked when it was introduced in the arcade version.
TBH I don't wavedash with Heihachi much anymore, I don't think electric abuse is an effective gameplan with him anyway. I'll close the space with dash into bf3 to get an f3 out of a dash. i18, -2 to -3 on block, face down head towards KD on normal hit and a potential wallsplat or CH launch, knee that hits low to the ground and even tracks to his left slightly... There is no reason not to abuse the crap out of that move, it is an absolute S tier move when used properly. I'll also just dash into block a lot more since getting as many pokes exchanged as possible is vital to Heihachi's gameplan so you can get a large volume of mids out to make the inevitable power low harder to read and blow up... and also make the opponent uncomfortable for being on the defensive as much as possible so he or she will attack more frequently and thus give me the openings I need to take the round.
Uuuhmm... I just started writing, not gonna check for errors, take away from that what you will and try to implement it into your game if possible (and call me out if you think I am full of shit and we'll discuss what's BS and what's legit
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Edit: Ch f3 buttflop with Kaz doesn't combo into anything... or I am not sure needs more testing.
