Perhaps the most distinctive thing about this Busou Shinki anime isn't its mecha musume designs. Those come courtesy of the figures, so the show doesn't get the credit. Nor is its top-flight CG fighting. Those come from 8-Bit, who made Infinite Stratos (another mecha musume anime) and helped out with Macross Frontier (a mecha anime with musume in it).
It isn't its moe moe character traits, some of which are straight out of Hand Maid May. Hell, it isn't even in its small-creatures-arena-battle premise. That comes from the likes of Danball Senki, Custom Robo, Beyblade, and Pokemon.
Well, everything I just listed does help make Busou Shinki fairly distinctive, but the real interesting point is actually one that doesn't have anything directly to do with the show itself.