If you are runing a team of all Batman and they are in sleath and your get attacked with pluse wave i know it ignores sleath once it is actived but if you cant see any of them to draw the line of fire to them to active it (becuse it says you must have a line of fire to alest one to active it

Since Stealth is not a wall, blocking terrain or elevated terrain it does not prevent the initial line of fire from being drawn.

Stealth doesn't work against those LoFs, so all of them can be seen before the powers are ignored.
Since Stealth none of those, the LoFs are not blocked.