BLUF: Should I use Metamorphosis in 4th BESM to simulate Digviolution? If not, what?

Hi all,

I'm largely new to BESM. I have some experience with systems akin to it like Hero System and Gurps, however. I wanted to run a Digimon game for my friends and I think I have it down but largely, I'm unsure how to handle digivolution.

For those not in the know, unlike Pokemon, Digimon only temporarily evolve then return to their base form (or lower) when the energy is expended. So this would be a limited transformation of something with a larger pool of power and abilities. I had thought to use Metamorphosis attribute as a purchasable attribute that would give them a low duration and recovery set back transformation.
Thoughts?