ISI is the combination of several groups, it was nothing new but a new name composing several groups. There's no such thing as remnants of Iraq's former army, the entire population were remnants of this army as conscription forced everyone in, infact Shi'a were the majority in the former army.1) In 2003, Sunni insurgents were the remnants of Saddam's Army. ISI was formed in 2006, at that time Maliki was appointed by Bush himself. His sectarian policies and Bush's divide and rule strategy pushed Sunnis to form ISI.
ISI used many different names as Shura council, Mujahideen Ansar al sunnah etc. This group was active before Maliki came to power.
Yet Assad is fighting YPG. Iraqi gov help to Peshmerga is not because of a strategy but our idiotic inclusive government with Kurds such as the Yazidi woman crying in parliament.2) Turkish government is the last to support such rival state. As you see, Assad helps YPG; Iraqi Shia gov helps Peshmerga, whole EU and USA assists Kurds. We keep our neutrality.
In Qamishli IS vs. Kurds+SAA
In Mosul Dam, IS vs. Peshmerga+Shias
In Ayn Al Arab, IS vs. Kurds+US led coalition
FSA is Sunni as well, ISIS slaughters them. You're not answering the question but at least you see what I mean now, you're blaming someone for being a mass murderer whilst supporting another mass murderer.3) I havent given one single coin to IS or ISIS or IS during the last 10 years time. My stance is based on political gains, thats all. Oops one minute, I am Sunni. I prefer Sunnis over Shias, Yazidis, Christians, Zardoshts, Jews, Communists. And thats natural. Same thing applies to them either. No reason to discuss about it, right!?