League of Legends (LoL) Question: akali counter

The best way to counter her is hard CC. Her strenght is in being able to dash in and out of a fight. She is also able to stealth and become untargetable. Taunts are ideal, because they stop her ability casts and reveal her in her stealth shroud. The next best counters are roots and stuns so that she can't dash away. Another good way is to use items like Morellonomicon and Executioner's Calling to keep her from healing off her abilities. Finally, any abilities that offer true sight are useful to keep her from using her cloak to get away.

Get early magic resist. Akali has limited burst because of her energy bar. After she uses combo -> shroud -> combo, an Akali that's out of energy is a sitting duck and you can just kill her. Also you can play aggressive if she uses her E to farm. Her energy problems and lack of sustained damage are pretty abusable.

Mid Lane Counters: Diana, Veigar (as long as you know how to farm and use your cage effectively), Annie, Zed

Top Lane Counters: Pantheon, Urgot, Ornn, Maokai, Darius

Play Pantheon!
Easiest game of your life! ^^
I am an Akali main myself and that is the only matchup I am almost never able to win.

If you don't want to play Pantheon: pick a champion with either very strong wave clear so she has to farm under her turret and delay her Hextech Gunblade powerspike, or a champion with great poke and just keep her low.

she sucks until she gets lvl 6, then her ult lets her kill everything. anyone who can put her behind early can potentially shut her down but apart from that you're gonna probably need ganks to kill her. Buying items that reduce healing like Morellonomicon or having Ignite can help as she relies on healing to help her live through sticky situations. having good waveclear can help too as it prevents her from pushing you in and diving you