[catwhowalks]

Ah, a subject that finally got me to cease my years of lurking and actually join up. Because I've actually been thinking of it for a while.

Assuming that Megaforce itself is mostly the same, I would have had an episode in which an evil team of pirate rangers appear and fight the Megaforce rangers. They would be defeated and Gosei would strip away their powers and turn them into keys, explaining that all the keys are powers that he's been collecting and in some cases repairing and restoring. He refuses to explain why.

At the end of Megaforce, with the Warstars defeated, Tommy suddenly appears as the White Ranger with his own alien team (DaiRanger suits) They had been working to free Master Vile's empire and had succeed, only for a worse empire to arise. The Warstars themselves were trying to conquer Earth because it was one of the last free planets they could find to flee to. Tommy has Rallied over a dozen alien Power Ranger teams to make a final stand on Earth, which has more surviving Ranger teams than anyone else. Gosei has been restoring and repairing lost and damage powers for that reason. Tommy's clone has even returned from the past with his copied Green Ranger powers to help.

Cue the big battle from GoKaiger, but use footage from the 199 heroes to have a big all-mecha battle against the alien general, who even clones some of their recent enemies to giant size to fight them.

The rangers win, but the Morphing Grid can't handle that many active Ranger powers all at once in the same place and it overloads. All powers in use are rendered damaged and unstable and cannot be used on their own. The only way to use any of them is to layer them on top of a stable set of powers. Fortunately they have some--the Pirate Ranger keys, which were unused during the big battle (Cutting out one Megazord from the big mecha battle should be doable) and thus unaffected. The Megaforce rangers are selected by the other to use them.

Meanwhile, while their main fleet is destroyed, the enemy empire is not defeated. Knowing most of the rangers are out of commission, they sent a rag-tag fleet of their surviving ships and misfit commanders to bid time until the fleet can be rebuilt.

The silver morpher would be created later by Gosei in an attempt to create a morpher that can tap into more of the keys powers at once, explaining his key merger ability. Orion's story was fine and can stay the same except for being given the morpher after landing on Earth.

In addition, they have to learn how to use each key set in order to unlock it's full abilities, so Gosei doesn't have to just randomly give them upgrades. Same basic idea as the Great Powers, but no one has to grant them manually.