Wolf and Lucas. And Ike. Also, arguably TL.
#Invalidated
Similar characters =/= clones.
In Melee, clone pairs like
-Dr. Mario + Mario
-Fox+Falco
-Marth+Roy
-Link+Young Link
-CF + Ganon
-Pichu + Pikachu
Had almost identical movesets and animations, with only minute differences (eg Mario is slightly more mobile than Dr.Mario but his moves do slightly less damage, same goes for Marth+Roy but Roy had fire, a scaling counter and his sword was WEAKER at the tip, Falco's lasers and shine were different from Fox's and he was slower, etc etc)
Wolf is not a 'clone' of anything. Not even close. His entire moveset is fundamentally different from that of both Fox and Falco. Yeah they're all Star Fox chars with lasers and a reflector, but if you look at the rest of their movesets, animations and playstyles you'll see they're not really similar enough to be 'clones'.
Ness and Lucas are somewhat similar but again they're just not similar enough to be labelled 'clones'. Not even close. Their attacks and movement styles are completely different.
Ike and Marth...are you serious? -.-
Their only similarities are that they're both from FE, they both have swords and they both have a downB counter.
With TL I suppose you could make a case of him being Link's clone but the similarity between TL and Brawl Link is much smaller than the similarity between Melee Link and YL. With those two, literally all their moves were the same except Link's were bigger and stronger, TL's arrows and sweetspot dair had fire, his upB was bigger and multihit and...actually I think that's it. They even moved in the same way, with Link just being a little slower.
In Brawl, TL and Link are almost completely opposite in their movement styles, though they do have all the same moves outside of the boomerang, bair, usmash and fair. If anything I'd label them semiclones.
The point still stands that the elimination (or attempt at it) of clones from Melee --> Brawl was one of the major changes between the two games. Dr. Mario, Roy and Pichu were completely removed, Falco and Ganon had quite a few of their moves changed and TL and Link were made completely opposite in their movement styles.
Also keep in mind that in the Metroid series, both Dark Samus and SA-X are meant to be literal clones of Samus (well...I guess it's arguable for Dark Samus but she turned out to be pretty much identical to Samus, just with a few additional capabilities that probably wouldn't work in Smash 4. With SA-X it's definitely not arguable). Including them in the next game would mean they either de-clone from the Metroid series (which wouldn't really make any sense) or stay true to the Metroid series and reintroduce clones in the smash series, which would defeat the purpose of all the changes they made between Melee and Brawl.