What if all or some of the generations of MLP were related to each other rather than separate series? Would their formats be different from the way they wound up with when they did air or just be the same? Could the nature of any of the characters be different as well or probably just remain the same only with the connections? What about certain episodes? Let me know what any of you would think if any of the generations were to be related.

I've seen lots of Fics where the events of G1 were ancient the precursors of ponies who would eventually found Equestria. The Pony POV Series went with the idea that the My Little Pony Tales were the future of G1, but had a societal collapse from the magic equivalent of a nuclear holocaust. Then it took millennia to rebuild and eventually became the Equestria of G4.
G3 has usually been explained as some alternate reality made from magic or by Discord.
Canon is fickle.

Heh, and then there are fics like mine (the so-called 'Firehooves Cycle'), where the gens go in reverse order, and all roads lead to g1. Lots of Brony/pony fan-writers have tried to tie all the gens together

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I like to joke that there’s a timeline depending how modern the world is

G1
G3
G4
Mlp tales
G5

If G4 really was to be a continuation of G1, then there would be a reason for Megan to be in it. However, she would have to understand that the ponies that she knew are no longer around and that being there is only equal to not much time back where she lives, which may explain why doesn't even look that old, but is shocked about the changes compared to when she was last there. Ponies such as the Royal Sisters and a few others that lived that long will still be able to remember her as they were pretty young when she was last there. In a fanfic such as mine known as, Destiny or Coincidence, the Mane 6 are actual descendants of ponies that she know when she was last there with Twilight Sparkle learning about her history by finding a hidden book about her. Even in my other fanfic, Royal Origins, I have it said that it was Megan herself who was responsible for giving the two future rulers their names by picking them up when they were fillies and seeing what they made her think of when giving them their names, though anything else they know about her is either mentioned by Posey and when they get the book about her from a fellow unicorn.

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Given the retcons FiM itself did, it's no less insane.
G3 was basically a magically engineered paradise, but the ponies also forgot how any of the magic world, so when their reality altering wishes began to contradict and pile up and was going to "crash" reality, it forced the Alicorns and Draconequi to do a save-state load.

Some are claiming that G5 is a continuation of G4 and saying that Twilight Sparkle might have failed to keep unity. However, this is mostly a theory brought by bronies online. What is interesting that when Sunny Starscout wakes up, there are dolls or figures of the Mane 6 there on her nightstand. When they even play with them, the Rarity one actually acts evil, but that's because those in her hometown thinks that the unicorns are evil. For some reason, they don't say anything about they view alicorns, but I guess it's because they aren't natural for the most part. Should G5 be made into an actual series and have Sunny remain an alicorn, she would be the first earth pony to become one, which would be interesting seeing that they don't have wings or a horn to start with unlike the other two groups.

Here are some split screens to show what it would be like if they were related.