This is how you deal with a Pyke:
Just stand behind minions and ..nvm, he just AOE stunned everyone and now looking for a point blank ult that you have no choice but to flash or die.
Ok, just play passive and farm under tower.. nvm, he just helped kill your mid.
Ok, pressure their adc he left unattended. ADC isn't stupid, backs off, meanwhile you are now pushed up hard. Pyke arrives! Enemy double kill.
Ok, just wait for jungler and all-in him. Jungler arrives! Oh, he's gone invis and made it to safety... Better luck next time, chumps.
This champ was made specifically to piss you off. It's part of his appeal. And he excels at it like no other. There will be no nerfs, he's apparently not overtuned enough or he would have been on Riots radar in 9.15. All we can do is deal with it.