I played games whit the possibility of stack units like Virtual Defence Or phantom Defence
how i can stack units?.Thanks

I'm assuming you know about hotkeying etc.
So bascially what allows you to stack is the "lights" being "turned off".
The lights are really shared vision, and the player is turning them off for themself, and everyone else.
There are 16 ai scripts relating to vision
Turn off shared vision (players 1-8)
Turn on shared vision (players 1-8)
Note: this trigger changes what is viewed by the player the trigger is firing for.
i.e.

Doesn't that only apply to stacking buildings? He wants to stack units.

Basically just burrow some units and unburrow them with any other unit and make sure to wall them off. Air units can be stacked easily just make sure they have hyper triggers so some of them don't lag behind.

Facts about stacking (not important)

My mistake, I misread the question.

Stacking units can be done how Tempz said, but I think that means that you can only effectively stack zerg burrowers right?

Well yes but a few zerg units mixed in with toss or terran will work so kind off =p

I'll have to look for the tutorial someone posted on here a while ago that involved stacking Marines, or if I can find the tutorial map in my files I'll be sure to post it.

I'm assuming it involves EUD or something complicated however i would like to see how he stacked units.

Please don't throw around the suggestion of EUDs if you don't know what you're talking about.

Stacking units can be performed by preplacing a disabled unit sprite, and then using "Set Doodad State" to enable them at the beginning of the game. This puts the units in an illegal frame, but you can issue them an order to move to be safe.

In summary:

1. Place a unit sprite for the unit you want to stack.
2. Select this sprite and in its properties, disable it (check "Active / Disabled (?)" in SCMDraft)
3. Using triggers:
     a. Enable the unit
     b. Order the unit to move

Keep in mind that if a player sees the unit before it has moved, the player will crash because the unit is displaying an illegal frame. Also, when a disabled unit sprite is enabled, a rock sprite is created a little to the north of the unit's position.

This trick works for many units, but not all units. See the attached map for an example of two Zerglings.

 

Attachments:

I could swear there was a method that creates and stacks units via triggers, without enabling sprites. I still can't find the damn map that explains it, though.

I'm pretty sure the only way to entirely remove the collision is the method I described above. Are you thinking about exploiting the walkable null tile and moving a bunch of units from it to a single walkable terrain tile? That's pseudo-stacking, where they all pile up because they can't walk anywhere else; it's very similar to what Tempz suggested above, except you aren't limited to burrowing Zerg units.

The only problem with this is, units won't walk over other units to get off of null, so the collision box of the units in the walkable area can't touch the edge of the null tiles, or new units won't go in.

Found the map. As far as I know, it has no preplaced sprites. It just does the disable/enable trick.

EDIT:
Nevermind, just looked in the top right corner and saw the Marine sprites.

Attachments:

www.staredit.net/starcraft/Sprites

Terran Marine (and Jim Raynor (Marine))
Terran Firebat (and Gui Montag)
Terran Ghost (and Sarah Kerrigan, Samir Duran, and Alexei Stukov)
Terran Civilian
Zerg Zergling (and Devouring One)
Protoss Dark Templar (and the hero variants)

these can stack under certain conditions (random, using a hack)
Zerg Larva (Makes all built units, not buildings, have same effect)
Zerg Hydralisk
Protoss Zealot

I thought I made a complete list somewhere of all the units which can stack, but I can't find it anymore. I think scv was one. Zealot was only stackable when I used a hack, and then it turned completely invisible. Hydras and larvae aren't 100% stable and can crash the game on start. The animation is what determines what is stackable and stable, so all units using the "ghost" unit image can stack, but since sarah kerrigan uses a different image, she can't stack. Likewise, all 3 dark templars can stack. There are a large number of buildings which will also stack, and you can walk completely over those.

You used to be able to stack burrowed units by unburrowing just after the unit burrows. I believe this was patched, and is now impossible. It was impossible with triggers as well, and if you burrow the unit, it gains its collision box again.

Cloaking is a different story. You can permanently cloak any burrowing unit simply by unburrowing as soon as the unit enters an arbiter's cloaking field. Likewise, the unit loses its cloak if it burrows. However, this can be performed via triggers easily, and much more units can cloak than can stack.