In the game Digimon World, how do you obtain MegaKabuterimon?

Izzy fell into a hole that leads to a selfish Digimon.
It took Izzy's thoughts which allowed Izzy to Forget and not caread about everything..
Without hope,Tentomon becamed moltimon and Pabumon sooner on.
Pabumon processed bubbles that allowed Izzy to look through the past .and finally came true
Izzy and Pabumon went into the storage and took back what that is rightfully belongs to Izzy.
Izzy was in troble when pabumon slowly convert to Tentomon again.
Tentomon digivolve to Kabuterimon.when kabuterimon was not strong enough.Izzy's creast of knowledge allowed Kabuterimon to Digivolve aagin.To Megakabuterimon.