He's not a classic champion. As champions come out, they are getting more unique and stronger than older champions, kinda like how new pokemon generations are stronger than the last and so on.
Just saying. You can also say the same for Zed, Yasuo, and Fizz, which all these champions have crazy outplay potential. I would argue the creator of Ekko made the perfect champion. A champion that can deal with most champions in the game, and make plays. He should not be destroyed, but should be a blueprint of how future champions should be.
Champions do have the right to have outplay. Eventually classic champions are being reworked, and stuff, and every 6 months or so there is big game updates with champions being changed around in their kits.
Anyhow, hes my favorite champion (Ekko). I think if anything, just take his movement speed he gets from his passive away, and that's all that should be done. I have said for over a year now the biggest problems is the items instead of the champions themselves. For example, Trinity Force just does too many things and gives every stat basically with the exception of a few like Crit and stuff. These items need to be tweaked, not the champions.
Gnar is probably going to be nerfed hard although really you can just nerf frozen mallet, and he will be put in place. Riot gets to nerfing champions and they get too weak.