[Utrommaniac]

A lot of elements are remaining, but with some changes

Namely:

Spoiler:

Just sticking the four or five main aliens on one planet. Which yes, is absolutely going to cause huge problems, but that's why they're fighting.

With the Utroms, Triceratons, and Neutrinos butting heads with each other while the Malignoids (and possibly Havlsh?) live in isolation to get away from the fighting. Unfortunately for one particular Malignoid hive, things go badly and when they get infected with the Cordyceps, they're the ones that spread it.

The turtles would very much be under the "reactionary murder hobos" moniker and their behavior plus every physical weakness they would pick up from spending most of their lives basically underground makes it possible that Shredder (now and Utrom again) is able to capture them easily and take them back to TCRI...only for that to turn out violent and they're tossed to Northhampton for "rehabilitation". Which is where each turtle really gets to grow outside of Splinter's helicoptering.

With that in mind...still gotta figure out how Yoshi's death was an accident.