[Original TMNT Cartoon Fan]

And the original series characters are called with MWS, Fred Wolf or 1987 before their name. Also, no fan characters! (except supporting "ordinary man or woman on the street" having a line or to). The different Earths are also refered to with these terms.

Maybe MWS Krang asks Chrell to repair the Technodrome? When Donatello and MWS Krang's portals open at the same time (which usually works), an ion storm in Dimension X opens portals to and between different Earths somehow?

Of course, characters like Tigerclaw and Hun can appear. As well as MWS Bebop and Rocksteady as good guys? Everything is possible when we write it as a story instead of playing.