C# 135 bytes

string[] g = {"Blinky", "Inky", "Pinky","Clyde"};
Console.WriteLine(String.Join(",",i.Contains("Pac-Man") ? g: g.Except(i).ToArray()));

(where i is a string array containing the input)

After looking at the other examples, I see that C# is rather a verbose language :)

C# 135 bytes126 bytes

string[] g{"Blinky","Inky","Pinky","Clyde"};Console.WriteLine(String.Join(",",i.Contains("Pac-Man")?g:g.Except(i).ToArray()));

(where i is a string array containing the input)

After looking at the other examples, I see that C# is rather a verbose language :)