It's been said that every time period is connected. Science cannot prove that a bend in Time-Space can happen, but it has.

When Megamen from every time period use their most powerful attacks in the same exact spot on earth, they rip open Time-Space and are flung to another dimention, one filled with ponies and magic. How will these creations of science survive protecting these magical ponies and warding off old and new enemies, not to mention each-other.

Link to the Knowledge Base: Megaman Knowledge Base

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MLP:FiM belongs to Hasbro and the Almighty Lauren Faust
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