Soul Stealer / Flash
Soul Stealer, as it is named in the command list, is Yoshimitsu's move unique only to him. The name "Flash" as the move is more infamously called comes from the flash of lights that covers him during a successful hit and causes the opponent crumple to the ground allowing for a follow-up. It is commonly mistaken as a reversal but it is an actual attack that has it's own hitbox and range. It serves as an ace in Yoshi's sleeve as it seemingly comes out of nowhere and can punish some characters' moves that are normally regarded as safe. By nature, it is used during a head to head clash making it a double edged sword that either swings the match in Yoshi's favor or can be the move responsible for the round loss.
In his default stance, it is the fastest move in the game at 6 frames but paired with practically 0 range that is near impossible to hit without a collision of hitboxes. An alternate input is [4~1] which is a frame slower but makes it possible to do the move with a forward motion. A new feature to Tekken 7, Flash can also be done from the while rising state giving him the ability to duck and flash. During No Sword Stance (NSS), Flash is slower at 8 frames but has more range and it reverts him back to 1SS. NSS [4~1] variation is a frame slower at 9 frames but similar to 1SS version, it can be used after an advance and as a filler in combos. Specific to NSS, another alternate input is fc 1+2 which comes out as Flash instead of the regular KIN transition.
1+4 - 6f
[4~1] - 7f
ws 1+4 - 6f
NSS 1+4 - 8f
NSS [4~1] - 9f
NSS fc 1+2 - 8f
NSS ws 1+4 - 8f
Flash as punish
As mentioned earlier, Flash is the fastest move in the game where the fastest move is usually seen at 10 frames. It may catch players inexperienced with the Yoshi match-up off guard as safe moves on block aren't so safe anymore. Picking up experience of which moves are Flash punishable is an exercise players must practice to make full use of this distinctive move.
Flash after opponent attack on block
Flash is a good defensive tool by nature. It can stop momentum where most players believe they have frame advantage. It is more effective against moves that advance opponents and leave them in point-blank range or very close enough for Flash to hit.
Flash after opponent attack on hit
A very risky option but it is possible to flash even after getting hit. Same as Flash after opponents attacks on block, opponents have more incentive to keep attacking after successful hits. Flashing when negative is highly not recommended as it can easily go awry but there are certain moments and situations where the risk can net you a very good reward.
Flash after player attack on block
Apart from being a good defensive move, Flash doubles as an offensive move as well. Yoshi has numerous moves that leave him negative or in very close range that can bait opponents into attacking him which can be a good placement of Flash.
Flash after player attack on hit
Certain moves and situations give Yoshi enough frame advantage for a guaranteed flash. It requires good execution and presence of mind to hit but learning these can lead to very big damage.
Flash on instinct
A usage that is hard to demonstrate but with enough experience, players will instinctively know when and where to Flash.
1+4, d+1+2 FLE 1+2, [3,4], cd+2 S! d+2,2,1 (63dmg)
1+4, iws4, d+2,1 S! d/f+1, d+2,2,1 (63dmg)
1+4, d+2,2, d/f+1, cd+2, d+2,2,1 (62dmg)
1+4, d+2,2, cd+1, f+3+4, FLE 2 (62dmg)
1+4, cd+2 S! d/f+1, 2, b+2,1~1+2 KIN f+2 (62dmg)
1+4, d+1+2 FLE 1+2, 2,1 S! f+3+4 FLE 2 (62dmg)
1+4, d+1+2 FLE 1+2, d/f+1,2 S! f+3+4 FLE 2 (62dmg)
1+4, d+2,1 S! d/f+1, b+2,1~1+2 KIN f+2 (61dmg)
1+4, d+2,2~2+3, cd+2 S! NSS f+3+4, 1, ff+2:2 (61dmg)
1+4, iws 4, 2,1 S! f+3+4, FLE 2 (61dmg)
1+4, iws 4, 2,3 S! f+3+4, FLE 2 (61dmg)
1+4, iws 4, b+2, cd+2 S! f+3+4, FLE 2 (61dmg)
1+4, iws 4, cd+2 S! d/f+1, b+2,1~1+2 KIN f+2 (61dmg)
1+4, d+1+2 FLE 1+2, cd+2, f+3+4 FLE 2 (60dmg)
NSS 1+4, [3~4]~U DGF 2, DGF 4 S! f+3+4, FLE 2 (67dmg)
NSS 1+4, f+3 S! d/f+1, 2, b+2,1~1+2 KIN f+2 (64dmg)
Contrary to what many players believe, Flash should not be relied upon as a panic move. It is very punishable on miss or block. Using the move in desperation or without reason develops bad habits that can easily be read by more experienced players who know the match-up.
Flash is a personal tool that different players will find effectiveness depending on their own specific play style. There are times it will be used constantly and times it won't see use at all. Knowing how to use flash is more important than worrying about using it all the time.
Flash can also be used to establish wariness in an opponent. You can expect an opponent who knows the dangers of flash will play differently. Showing opponents you're capable of using it can limit opponent's offense and give players some breathing room.