If a Giant model is in base contact with a collosal can he use this ability? Since Pulsewave is a ranged, can he use this ability?

Big figure Sinestro can make a ranged combat attack against any character in range, even if enemy
characters are in an adjacent square. Big figure Sinestro may make ranged attacks against figures in
adjacent squares.

Yes he can.

Sorry, no, he can't. Pulse Wave is a Ranged Combat Action and doesn't work with the Anti-Monitor's ability to use Ranged Combat Attacks when adjacent. I know. It stinks. I get hosed by that every time I play him without his Sinestro Corps for backup.

As for the Giants blocking LOF, Pulse wave states:
(Draw lines of fire to every character (friendly and opposing) within range in
every direction; these lines of fire ignore characters, but are affected normally by terrain.)
So even if a character is in front of him then he is ignored by LOF for Pulse wave Right??

If you can make a ranged combat attack, you can be given the appropriate action to make such an attack.

Yes he can. Let's look at the paragraph that prevents ranged combat while adjacent to an enemy:
So the fact that Anti-Monitor can make ranged attacks when adjacent overrides this limitation, and he can use Pulse Wave when based.

Another quote that might help against the confusion:

So even if a Giant character is adjacent, then a collosal can still make ranged attacks?

Because the anti-monitor rules state only.

The ANTI-MONITOR can be adjacent to a maximum of 12 squares. He can attack and be attacked
through any of them. The ANTI-MONITOR can make a ranged combat attack against any character in
range, even if that character is in an adjacent square.
Lines of fire drawn to and from the ANTI-MONITOR are not blocked by standard characters
(characters with the damage symbol), but they are blocked by giant characters (characters with
the damage symbol) and other colossal characters. Blocking terrain blocks a line of fire drawn to or from the Anti-Monitor


I just want to know the answer, so in the future when I fight one of these again. I can build some strategy against them

Thanks

Giants do block SCAM's LOF... but just because LOF is blocked, doesn't necessarily mean that a ranged combat attack can't happen (usually it does, but not always).

SCAM can use TIME TO FEED even if an opposing character is adjacent.

Well, that makes that much better. I'll have to bookmark this so I can underline it in my rulebook when I get the chance. Always hated that terminology...