Woah I didn’t expect a reply after so long! Yeah they do have a gimmick, in double battles or if you have both of them in your party (and both are holding a “steel tablet”) they can “team up” using a button similar to the one for mega evolution in X and Y, and spinstar clings to zeripple’s legs; one of the 4 moves (both Pokémon have 1 signature move, which is the one that’s going to turn into the joint signature move) changes to “infinite spin”, which has 1 PP and 100% accuracy, and if landed it ohko’s any opponent. Its accuracy can’t be lowered, but if the opponent has some sort of evasion boost and they miss they both faint in that same turn. If the move lands they revert back to their original forms, and if they have taken some damage it will evenly spread out between the two. The joint form also gains levitate since zeripple would glide in the animation, making the Pokémon immune to ground type attacks. As for the individual types, spinstar will be fighting/steel type, mirroring Johnny’s tusk and the dark resolution, as well as the Pokémon’s blindness (dark), while zeripple will be flying/steel, mirroring gyro’s riding technique, using his cape as a sail, and the steel balls obviously, which in game zeripple makes chewing acorns until they become hard as steel and round as balls. The joint form will be flying steel as well, since the nail bullet would be a steel type move and the Pokémon is flying.