My personal proposition for a meele carry
Random thinking got me to a skill that should make the meele carry champion actualy work the intended way. Since main problem of meele carry is that he gets blown up by 5 ppl every time he tries to get into the fight, how about making meele carry that can duel ppl in the middle of a teamfight. You can create a kit that is quite equal in dueling all the diverse roles so enemies wont feel fked just because you duel them, so its a detail.
The thing that can make a meele carry viable is a tweaked poppy ult. For poppy its toxic because she doesnt realy get any drawback for using the skill, its just "ult their support and wreck everything".
But if we tweak it so a)champion who "duels" another champion can only be dealt dmg from that champion (and towers and jungle etc) and only deal damage to that champion b)you have a specific range that you cant leave or the "duell" gets broken and others can kill you c)and "duell" gets a reset once you win one aka kill the enemy then we can make a meele carry that just duels the enemy despite his surroundings, by ballancing the kit etc you can make it so the duels will be quite equal vs diferent opponents and skill based for the carry himself
this would fit fiora suprisingly well as she is the "Grand duelist", and there were rumors of a)her being up for some reworking b)her intended role being close to a meele carry