Your "Dream Team"

[Paulbot]

Imagine there's a time paradox allowing all different Transformers from every continuity exist in a single time (I know, it's an out there concept).

Yep, it's called Transformers Universe

This is similar to an idea I was going to post.

It's also similar to how I imagine the "Universe" universe -- as being like Marvel Comics "Exiles" series: various TFs taken from different realities fighting alongside or against each other.