how do you think marth reacts whenever smash bros puts a different iteration of link on the roster???
(like how melee was OoT Link, ssbb was TP, ssbu was BOTW AND (child) OoT)!!!
He would definitely be very confused at first XD
The first time he met tp link in brawl he went to see him and was like "heyyy Link! Wow you have changed since melee! I like your new tunic! :D" and Link would be like "what? Wtf are you talking about? WHO ARE YOU???" And Marth wouldn't understand until Mario tells him it's not the same link as the one he met back in melee
But they would become friends (and more hehe), and since tp Link is also the link of ssb for 3ds and wiiu, Marth would think he's gonna stay forever with him in smash, and that no other link could replace him
...
But we know what happened lmao
When he met botw Link he was like "ANOTHER Link?? You must be kidding me..." And he would be very sad tp Link was replaced.
As for young oot link... I think it would confuse him even more than the fact there are several Link. Because wdym that pretty hylian guy who was obviously an adult is now a kid??? What the fuck happened??????