It is true that Shri Krishna was God, he could have killed everyone himself and saved several people who deserved to live but it was very important for Pandavas and their supporters to do this battle on their own so Krishna can spread the following messages thrugh them: 1) Teach people that good always wins against evil. 2) you must always side with truth no matter what personal sacrifies you have to make. 3) Respecting your elders is good but do not bear injustice as this will only encourage people to follow the wrong path and more more such valauable teaching.
A lot of people says he supports pandavs indiscrimately but that's not truth because he reprimaded Draupadi, Arjun, Bhim, etc as needed when they were out of line as well. For ex: He reprimanded Arjun for speaking disrespectifully about Karna, Draupadi for considering her insult was so great that it was okay to just fight, loosing several innocent lives, without giving peace a chance.
Some say Draupadi disrespected Duryodhna and brought about the dice game but be truthful, when you see someone falling your first reaction is to laugh. It's not right but it's human nature. What Duryodhan did was way out of line, bhabhi was and is considered as your mother and to try and disrobe your mother is an unpardonable crime.
Krishna was said to have used trickery in bring about the death of Bhishma, Drona, Karna etc. The point is that they had to die.
Bhisma himself told Yudhisthar that bring a woman in front of me and I will drop my weapons, Shri Krishna had to suggest Sikhandani's name as Mahadev gave Amba this boon that your will be responsible for Bishma's death.
Dristhadum was born to kill Drona. He could never kill drona in a fight so Drona himself taught him and gave him a boon that if circumstances demand then I give you the right to kill me. In fighting against pandavs drona forgot his words so Krishna suggested a way which wil cause Drona to drop his weapons making it easy for dristhadum to kill him.
karna might have been daanveer but he supported his friend blindly to the extend that he called Draupadi a prostitute. He had to be killed as well. Karna was cursed by his teacher Shri Parshuram that his Vidya will leave him at the time he needs it the most, plus Karna helped kill an unarmed Abhimanyu, a 12 year old kid by trick so he did not deserve to die the death of a warrior.
Bhim was bound by his oath to kill Duryodhna by breaking his thigh. Gandhari knew her son is wrong but she still misused her powers to make her son as strong as Vajra so no weapon could kill him. Shri Krishna first tricked duryodhna to ensure his thighs did not become of vajra and then reminded bhim to fulfil his oath.
Everything he did was to protect dharma but despite being a God his still honoured Gandhari's shrap and accepted the full destruction of yadhuvanshi's to fulfil it.
These are not the actions of a Villian.