You don't dodge cho's rupture, its the cho player that completely misses them, and if he's having a hard time hitting you, all he has to do is use it on the minion wave instead and suddenly he's avoiding your harassment and farming at the same time. With movespeed 2 boots, a rupture centered under your feet is nigh impossible to dodge.
Mundo's cleaver is a good counter to any tank, but its like any skillshot. Stand an inch behind a minion, and it gets completely denied. I know it'll be pretty hard to find anyone doing a solo lane after his nerf, but try it sometime. Cho was repeately nerfed for a reason, a good one. Dont be so naive to think it was because of his ultimate, it was because of his stupid solo lane potential, you don't even have to be good as cho to deny 90% of all champions in a solo lane as him. He's still pretty hard to deny, he just won't be one shotting people with his ultimate as often.
The only true difference comes when you get your ultimate. Your ultimate is your best chance to get even at cho, and even then it depends alot on what situation you've put yourself him. It needs to be a good ultimate though, that does damage and keeps him in place. Malzahar's ulti followed by his E and ignite is agood option, but you need take a good chunk of his healt first.
There are only two champions that can counter cho with some consistency. Corki and Kog maw, altough kog maw will have a much harder time then corki. Kog needs to waste a good chunk of his mana to harass, as he'll rarely get close enough to autoattack. Corki has an easier time because he does awesome true damage and has his own methods of escape.