String advice/ What they use?

[Goose72]

Can anyone make a guess at what kinds of strings some of these artists use? I know that Flea uses GHS, Tim Commerford is supposedly and Ernie Ball guy, but what kind of strings...i.e. nickel rounds, flats, or what? Some other sounds I am trying to obtain are like the bass tone on Paramore's "That what you get," Alkaline Trio's "Calling all Skeletons," Foo Fighters' "Learn to fly," Daughtry's "Home". Would you guess that these guys use Nickel rounds? Maybe a couple weeks old or so? Their tone seems so mellow and just bassy, not twangy/zingy that you get from SS strings...or are these flats??

Thanks for your input!