The card of SaberLeomon reveals he is a Mega. He has to be to destroy MetalEtemon. Anyway, that means Leomon is an Ultimate. Keep that in mind.
There is a card called MarineDevimon, an Ultimate form, which says it can digivolve from Devimon. Therefore, the Devimon card must be a Champion, even though I don't have that card. So, Leomon is an Ultimate and Devimon is a Champion? Why is Devimon so much stronger?