They just want their home back.
http://www.serebii.net/movies/genesect/After escaping from Team Plasma, the Genesect get distressed because the place they knew as their home before they died has been completely changed by sweeping snowstorms. They head to New Tork City wanting to regain their former home. Mewtwo senses their voices as, just like the Genesect, it too was created by human hands, born from the genes of Mew. Ash and friends arrive in New Tork City, having travelled there in order to check out Pokemon Hills but then the Genesect show up, and the super fast Red Genesect fires off an energy ball towards Satoshi and the other yelling out "ELIMNATE THE ENEMY". Mewtwo sweeps in and blocks the attack. It says that it understands how the Genesect feel - it too was not meant to exist in this world but despite that, it's still going to stop them from attacking the Pokemon of the city. The two clash, the shockwaves from their incredible fight flying all through the city. Does Mewtwo display its true power after awakening? How does this battle guided by fate end? Ash promises to take the Genesect to their home. How will he an Pikachu manage to fulfill their promise and save the city!?
