Cable is a monster alongside Apocalypse. I asked the same question back in the day and got the answer that Cable is perfectly fine at r2, but I honestly have had no regrets about ignoring that advice and taking him to r3.I'm not sure why people are asking you if he's duped or not. In my experience, that dupe is...well, not entirely worthless, but certainly not something that a rank-up would hinge on. You occasionally get a power gain buff, and that's about it. Since 99% of his damage comes from his degens, and those degens come from his heavy attacks, more power isn't all that useful.
I've got a 5* Apocalypse, who's going to R5 soon. Is Cable worth R3?Other 6* R3 mutant options include Storm, Colossus, Rogue, and Jubilee.