How are you supposed to play sluggish champions nowadays?

How are you supposed to play champions like (Sad, because he was just reworked and no one touches him) (yes im aware he's overtunes atm, but still falls into this category) and some others who rely on sticking to their enemy when nearly every new and reworked champ has oppressive amounts of mobility in their kit? Aside Urgot, these champions don't even have higher bulk for their lack of mobility(especially Paperkaiser) literally have no way of dealing with it since they mostly use slows to catch their enemies when dashes ignore slows entirely. These champs were supposed to fight against tanks but tanks are basically extinct and all you face now are speedy bruisers that out dps you or assassins who just poke until they can all in burst you.

Yeah, I get it, no one wants to watch stuff like or in LCS games because they are boring to watch, but you don't have to make every champ dash around the screen 24/7, it might be fun to watch, but it's not fun to play against. Might as well retire and delete immobile champs at this point.