Well, I don't do a lot
of that sort of thing, although if you're talking crossing toylines in my mind, "Classics," "Universe 2.0," "Generations," and "Reveal the Shield," are all extensions of the same thing. If you look at it differently, then I do much more of this then I think!
If you're talking using one character to represent another, then in trying to put together a season one cast, I repurposed Grappel as Hauler. (Someone just needs to make me a good Classics style G1 Gears!)
And for the Decepticons, Real Gear Booster X10 became my Lazerbeak.
Finally, since Animated Arcee is a distinct character from G1 Arcee, her presence (with a new head and weapons) in my Classics collection would, I think, count.
(I have shared these photos in the past, I am sure. But any excuse to show off!