Actually i know better than you if Akali it's viable or not at High elo.
Anyways akali it's tier 2
* Tier 1: Ashe, Janna, Morgana
* Tier 2: Sona, Miss Fortune, Galio, Kassadin, Kog'Maw, Kennen, Anivia, Twisted Fate, Amumu, Pantheon, Garen, Tristana, Gragas, Vladimir, Twitch, Shen, Akali...