[guncannon109]

I would've had some build up to the Super Mega Mode in Megaforce. Say each of the five rangers gets a focus episode in which they find one of the Ranger Keys to unlock their new powers for the second season only they can't use them. Then in Super Megaforce, it's revealed that Tensou had been working on harnessing the power contained with the five keys that the rangers had found and gives the team their Legendary Morphers upon Gosei's instruction proclaiming that they have earned the power of the legendary keys they discovered/unlocked in battle.