MOTHER 2 to MOTHER 3 transition theory
I think the event the Leder decribes in MOTHER 3 is the same event that Buzz Buzz decribes in the beginning of MOTHER 2. Basically, the world is starting to be destroyed, but Gyiyg uses his powers to stop the world from destroying itself so he can rule it with his evil power. Since Ness and co. killed Gyiyg in the Cave of The Past, Gyiyg was never there 10 years after MOTHER 2 and the world was destroyed. Thus causing the events prior to MOTHER 3, the white ship to come, and take the survivors to the Nowhere Islands, and they began their new lives as simple town's folk.
I think the event the Leder decribes in MOTHER 3 is the same event that Buzz Buzz decribes in the beginning of MOTHER 2. Basically, the world is starting to be destroyed, but Gyiyg uses his powers to stop the world from destroying itself so he can rule it with his evil power. Since Ness and co. killed Gyiyg in the Cave of The Past, Gyiyg was never there 10 years after MOTHER 2 and the world was destroyed. Thus causing the events prior to MOTHER 3, the white ship to come, and take the survivors to the Nowhere Islands, and they began their new lives as simple town's folk.