Rules for progression will be set by the individual guild.

My guild follows a simple run. We cannot consider it a Paradox clear if any of the members were from an outside source. Does not matter if it is 1/8 pugs, 2/8 pugs or 7/8 pugs it is all the same to us

Even if our guild did 90% of the work even if the pug was dead the whole time. It was still not a guild accomplishment.

So it is 100% or 0% credit in my guilds case. But no there is no set policy it will vary willy depending on who you ask.