I've been thinking if rines can attack with flamethrowers, tanks attack like lurkers and stuff. Is that possible with triggers?
No, it can only be done with a mod. It's a question rather than a concept.
So, there isn't really any thinking involved for something impossible, although you can cloak some units and move them beside a certain unit to achieve a similar effect.
Ha, i never thought of that

. Still Screwed is right. you can't really do somthing like that. What you can do is somthing like.. Say IN legacys Map where you drop a unit and it could shoot a lurker attack. If thats somthing like what you want i could show you his map

.
ยป Moved to Map Assistance
Yea this seems Nessecary for map assistance. I think this trigger is possible over all. But not in a way or as well as you want it to be without mods

there was a world long time ago where marines shot bullets firebats shot flames and there was another world were nothing was impossible marines could shot flames and that world was...Starcraft!
nah it can't be done unless you mod it(it can only be done in modding)
You could probably use the moved bunker system to create the illusion that a marine was firing a flamethrower, but it will only work for emulating the attacks of units that are bunkerable, and will probably be somewhat awkward.
Alternatively you could use trigger-based special effects to create something that looked (vaguely) like a new attack, and then some sort of virtual HP system to give damage capacity to the new attacks, but that's a good bit of work and still may not create the effect that you are looking for.
For the tank you could have a burrowed lurker and then a tank over it. Then use the trigger 'move location' on the tank and have the lurker move under the tank/tank's location . I didn't try this but It should work.
wow thanks for the response. However, I noticed that some units' attacks (lurkers, firebats, rines) have their attack as sprites in xtra editor. So, is there anyway to replace the sprite of the attacking unit with sprite of another units' attack?
You know what would be

ing awesome? If SI found a way to incorporate weapon detection into the tirggers.
Like:
Condition:
- Current player commands at least 1 Gauss Rifle.
Action:
- Center location labeled 'location 1' on Gauss Rifle owned by current player at 'anywhere'
- Remove 1 Gauss Rifle for current player at 'location 1'
- Create 1 zerg zergling at 'location 1' for current player.
That could definitely produce some interesting effects.
Another cool idea would be to add in a RetroGRP plugin to SCMDraft, turning each map into it's own mod (of sorts), might not work, but then again....
....sigh*
QUOTE
Condition:
- Current player commands at least 1 Gauss Rifle.
Action:
- Center location labeled 'location 1' on Gauss Rifle owned by current player at 'anywhere'
- Remove 1 Gauss Rifle for current player at 'location 1'
- Create 1 zerg zergling at 'location 1' for current player.
that won't work because map editor don't detect the weapons as units to be removed wich means that the remove trigger only works for units buildings resources and map revealers and that won't work i guess
what you can do is center a location always on marine and have another location where a reaver is shooting scarabs and when marines wants to attack move on of those scarabs and have it patrol marine's location so it goes to attack the only problem is to know when the marine attacks anyways it's a good idea if you can controll it
Why can't you just use firebats and lurkers instead of marines and tanks?
Besides mods, the only way to make an attack look like another unit's attack is to have the other unit around doing the attacking for you (like a lurker under the tank)