I was thinking i'd make a champion counter list! But i'd love your help! Post counters for junglers, solo and duo lanes! And i'll put characters that simply doesn't counter and doesn't need to be countered on the Useless character list! (all up-voted (+2 votes) comments come on the lists!)
Akali: Skillshots, Sustain, Long range. For example Swain, Gragas and Kennen. (and Lee Sin, general counter for stealth) High health counters Akali very well also.
Alistar: Amazing Sustain, Alistar will get oom. For example Warwick, Nidalee and Nocturne.
Cho'Gath: High sustained dmg that doesn't rely on spells. For example Gangplank and Nocturne.
Gangplank: Higher burst, Dorians shield. For example Rumble, Vladmir and Teemo.
Veigar: Long range
Amumu: Gank before he gets blue and he's gonna jungle very slowly.
Fiddlesticks: Gank before he gets blue and he's gonna jungle very slowly.
Vayne: Lee Sin, General counter for stealth