I'm very sorry if this has been covered before, but can you have an entirely Renegade squad 40 points with no Rebels and no Imperials?

Yep, there are two very common and mean lists out there at the moment. However both require two core sets to pull off (extra cards needed for the second list).

2 Elite Trandoshans

2 Regular Trandoshans

1 Elite Nexu

or

4 Regular Trandoshans

2 Elite Nexu

How does that list deal with some of the big hitters like Vader, Weiss and RGC ?

I don't they can do very well with that low of acts vs a 7 act Vader or 8 act RGC. I pretty sure 9act would have no trouble with something like that. That being said I think you need to add some rebels with the mercs and they can do ok then because of tempo.

And what are those lists ? I'm not too up on the developing meta.

My friend is thinking along the lines of:

IG-88

Elite Trandoshans

Trandoshans

Elite Nexu

Nexu

For 39 points. He likes the movement and hall blocking of the Nexu, Trandoshans are Trandoshans, and IG-88 can be either damage or tank with that Recover 3.

4x Trandoshan Hunter

2x Elite Nexu

Massive amounts of strain, and the hunters can pump out close range damage or go for objectives.

And what are those lists ? I'm not too up on the developing meta.

Causing stupid amounts of strain and the bleed condition really cut down on the activations available. The elite nexu are actually quite survivable and the free Bleed and Cleave 2 attack from 9 spaces away is really brutal.