In a Dragon Ball Heroes animation, Goku, Trunks, Vegeta and Cooler are seen fighting the saiyan who is going to be the bad guy in the new Dragon Ball Heroes anime. Is Cooler a "good guy" in Dragon Ball Heroes?
The answer to your question would be very likely be a No. Cooler is an antagonist and is a character who wants to eradicate the Saiyans just like Freiza. There is absolutely no reason for him to turn "Good", as that would imply, Cooler would be willing to fight Frieza to protect Goku and the rest of the Saiyans, which doesn't make sense. Cooler certainly hates Frieza and would destroy him if he had the chance. You could compare it to a relationship between Early Vegeta and Goku, where Vegeta would destroy Goku by himself if he could but you wouldn't necessarily see him join an arch enemy like Frieza and help him defeat Goku.
I believe just like Dragon Ball Fighter Z and even in the tournament of power, Cooler has possibly teamed up with the Saiyans to take out an even greater threat.