all a matter of opinion my friends,,and this is my opinion
not only do i think that stalone would place ahead of cena in a bodybuilding contest in his younger years,,i am pretty sure he would place ahead of cena in a bodybuilding competition now days in his early 60s
i dont say it just because i cant back out,,there is nothing to back out from,,stalone is couple of levels above cena,,genetic wize,,natural build wize,,training wize,,
stalone was NEVER a bodybuilder,,cena was,,
stalone is a product of the 60s and 70s where there was no growth hormones going around and no slin,,,he didnt have those products around him that blow you up to new dimentions and work a magic together if used right,,
cena is a kid from 2000 that got to his very average development of a amatuer due to the fact all the the drugs/powders were available to him and then some,,especially american growth and insulin,,and even though he used all that he still couldnt place no where to be remembered,,,thus the move to wrestling!
you are comparing someone who put all his life in bodybuilding and lived it including used every drug in the book and off the book to someone who was not a bodybuilder and didnt try to be a bodybuilder,,someone who liked bodybuilding but didnt go to the super extreme inorder to be one!
cena is bigger but also a lot taller,,when you see him 230 or 225lb or whatever he is,,dont forget he is 6'1 or more,,this is very tall for bodybuilding,,and unless you are a german

or eastern europian you wont have much chance to do damage with this height,,
stalone is a short guy,,if bodybuilding was his job he would do well at it exactly like he did with his acting career and movies,,he wouldnt compete with cena same class due to weight/height diff,,but stalone would win his class while cena wouldnt,,
im talking same conditions,,same drugs,,same training/hour in the gyms,,diet,,etc
when i think about stalone as a bodybuilder,,with less drugs less symetric frank zane come to mind,,with more drugs in the late 90s and 2000s matarazza comes to mind,,
when i think about cena as a bodybuilder,,um a taller version of branch come to mind,,the only thing is cena used as much as branch did and couldnt pack on the mass or condition or muscularity that branch did thus branch got a pro card and cena said bye bye to bodybuilding and went wrestling