Sooo, just checked and the least modified champions since season 1 (and 2) are ....
Here is a top 4 of the most unmodified champion since end of season 1 (and 2). Functionality, bug fixes, Qol, Twi.TreeL, Dominion and General systemic changes are not calculated.
First places: Wukong tied with Karthus. Wukong only got a double nerf to his Q in season 4 , Q losing 20% armor shred at level 1 and Ultimate losing 10% AD ratio. Karthus got a E nerf in season 3, losing 5% AP ratio on E. He then received a W nerf in season 5, losing 20 / 25 / 30 / 35 / 40% slow after 1 second of initial slow duration.
Second place : Pantheon. He got his first nerf in season 4, losing some attack speed and attack speed delay. In season 5, he get back most of his previous attack speed nerf and the totality of his lost attack speed delay. In season 6, he receive nerf (mostly) and up (a bit) to his Ultimate and his E.
Third Place : Tryndamere. He got an ASPD Up as well a fury duration UP in season 3. Later in season 3, he got his AP ratio on Q nerfed. Again later in season 3, he got his E cool down reset nerfed. And finally in season 6, he got his Ultimate slightly UPed.
They only remember our sacred monkey when they need to sell their stuff.

[slayer-pantheon-thumbs]
, but
and pointclick / enemy dependent, R takes too long to deal damage and all that damage can be easily lifestealed / denied by items or CC + shields,healing by supports (assuming you'd last long in teamfight).
). His W is the worst clone mechanic in the game considering
and
can both move and attack with their clones (when he SHOULD have the best clone mechanic considering his pedigree) and to top it off, all his power is put into his Ult, which needs to reach level 3 to be REALLY effective .
. E>AA>Q>R, deleted. Should note he's riding it out on
. Other than that, get a ghost blade and get to the back line, but that's more a skill expression of the role, not the champ.
's ult used to be truely global. It was nerfed at the same time as
's ult.
, heres to hoping riot doesn't find out or the rest of boards, or else he will soon be full of gimmicks like every other new thing in this game because of change for the sake of change (if riot finds out or people get salty enough).