Many species of amphibians, fish, arthropods and even certain reptiles go through metamorphosis. But, to my knowledge, there are no mammals that go through metamorphosis.
Let's say I want there to be a mammal species that goes through a metamorphosis. During this metamorphosis they would start and finish puberty, hit their major growth spurt and grow 1.5-2.5 times their size.
What I'm asking is: could a metamorphosis of this scale work? If it couldn't, why not and how could I make it work?