Hi There 
So as the title says what is an unblockable setup is?
Doing XXX after a knockdown, then doing some jumpin attack which the opponent is unable to block*
XXX = Whiffing a normal / special, walking some steps back, dashing forward, whatever causes possible safejumps.
some jumpin attack = Depending on character and opponent. Has to be a jumpin that can crossup. Wonky hitboxes are a bonus.
unable to block = If the opponent holds back, it hits in front; If the opponent holds forward, it hits crossup so no matter what he does, he gets hit. Can be “just frame” blocked, meaning that he doesn’t hold back, but presses back in the exact same frame that your jumpin hits. This will block the attack, but is extremely difficult to execute and not practical.
Here’s one I recorded a moment ago:
[media=youtube]yRX0a0ePu48[/media]
Notice that Ryu can’t block this no matter which direction he holds. Interestingly enough, if he tries to block it as a x-up, the jabs don’t link. The last part of the vid shows how to block it. If you tap down at just the right moment you can block it as a x-up (I just use a fireball motion). Depending on how you time it, you can make the jumping attack whiff completely. You could also possibly do a “just frame” block, but I find it easier to duck first then block.
Another weird thing about this setup (probably applies to many other situations) is that if you try to do cr.hp, you can see the move startup, but sometimes it doesn’t register as a counter-hit. I need to test some more to figure out why that happens.
A set-up that abuses the properties of how blocks and direction-switching will alter their hit box, so that no matter which direction an opponent blocks, it will always hit on the other side.
Of course, depending on the unblockable, there may be ways out of the situation, such as an invulnerable DP, or using another similar move to reset yourself out of the situation, but they’re usually extremely ambiguous and difficult to escape, at the cost of being difficult to execute reliably.
There are almost no true unblockables, they are mainly (as UD and Gems put it) “hard-to-blockables”. To block an unblockable setup you need to block one frame before the correct side. Any less than one frame hits you on the other side.
It’s actually setup-specific. Some setups give you more time to block than others, and other setups like the one I posted require you to do stuff like crouch first before blocking.
Well obviously the more leniency you have, the less “unblockable” it is. I’m talking about the most severe for the sake of example.
It doesn’t have to be a jump-in, btw. There’s a lot of variations. For instance, Sakura has can do unblockable tatsus on crouchers. Also, some set-ups will only work if they try to block, and they’ll whiff if they stay neutral. Fun stuff.
… do you mean it just hits overhead? Are you going to tell us about Zangief’s unblockable throw setups next?
No, he means that if the opponent crouches, the tatsu can cross up and, like classic “unblockables” hits front/back depending on which direction the opponent held.
If the opponent standblocks it, it doesn’t crossup though since it can’t fly over the head of standing people and thus can be blocked rather easily.
My bad, that makes more sense.
Lol if you’re gonna be sardonic, at least know the game a bit. Tatsu doesn’t even hit overhead.
Anyways, I wouldn’t be surprised if any cross-up can be occasionally unblockable, like psycho crusher or Blanka ultra.