[{quoted}](name=I Eat Ąss,realm=NA,application-id=3ErqAdtq,discussion-id=AHdaJkmM,comment-id=0000,timestamp=2018-03-08T23:38:42.362+0000)
Other champions have annoying things about them, but those 2 have absolutely 0 counterplay in that game mode
If I'm against Karthus, if I'm AP I can buy:
potentially
or
If I'm AD

As a tank I have a massive list of items, Karthus has fuck all for AD so I can stack the shit out of MR

plus I could always get the above AD/AP items based on any scalings I have.
And we can really make Karthus cry with: 
Not to mention there are a bunch of champs with innate abilities or tank stats that make them care less about Karthus:
... I won't go on, but I've only made it to F on the champ list.
Teemo is hard fucking countered by
and
If that's not enough the majority of Teemo's will build full AP so all of the above listed for Karthus applies. If they do have some versatility its harder to itemize, but also the shrooms are drastically less dangerous.
There are plenty of champions that are equally obnoxious to play against - and some are straight up harder to counter.
can start his strat by 5 manning mid at the start of the game, so you wont have time to amass gold to itemize against him, and he is capable of taking towers so fast you can win in under 10 minutes if the opponent can't scrape enough kills together.
also can nuke towers early game and can force down mid.
all have really good AD and AP scalings making them incredibly hard to itemize against.
can be AD AP or tank and can abuse the soul mechanic (if one thresh never collects souls they will generate souls faster for your AD/AP thresh to harvest) to get immense burst that can even threaten tank champs.
It's stupid to say that Karthus and Teemo out of all of the crazy combinations that exist in the game are the sole champions that are "too un-fun" and it's ludicrous to claim that there is no counterplay for them.