Chrono 4: Mecha Lavos' Re-Revenge - As it turns out, someone else was gathering DNA to create the ultimate fighting android to defeat Crono & Co...with the combined might of Azala, Queen Zeal, Schala, Magus, Dalton, the Mammon Machine, Cyrus, Masa & Mune, Mother Brain, Spekkio, Lavos, & Crono & Co. themselves...! Maybe a few DBZ characters just for good measure...>_>
When you think about it, Crono would have a tough time against the Metroids themselves...especially some of the later forms...it might be kind of difficult for him to do without a way to freeze them first...