:lol @ the thought of the fusion being able to take out Edo Madara. Dafuq? It's like people haven't read the Manga.
Edo Madara and people stronger than him would still shit on the fusion. The strongest they'd defeat are people below BM Naruto's level, because even BM Naruto would defeat this fusion with moderate difficulty. So I'd say the strongest the fusion defeats would be Nagato. Can also defeat Momoshiki (unfused w/ no Ninjutsu absorbed, but only if that black thing he used on Naruto isn't part of his own abilities) and Kinshiki.