My friend Nick plays space wolves and we have a sort of understanding (in DE terms 'You scratch my back I stick a knife in yours') we've got a pretty good strategy to kill stuff. He softens them up since he's got the good armour I blow them up with my dark lances and fancy guns.
However in terms of fluff its an interesting one. I like to write fluff and my current WIP involves a unofficial alliance between the space wolves of The Maw (Nick's army) and the Kabal of Blissful Murder primarily centred around the saving of a human colony from a tyranid invasion (the DE where there with recruits just to practice killing stuff) and the sharing of information regarding the discovery of a tyranid sub-species called Night Crawlers. All in all they're a good choice since unlike most space marines they don't hate aliens simply because they're aliens they are fiercely protective of humans though so a condition of my unofficial alliance is the KBM don't raid any human settlements that are under The Maw's protection.