In an ideal gas mixture, how does each individual affect the other gases in the mixture?
Not at all......
In real gases, there is substantial space around the individual gaseous particles. In an Ideal Gas, not only is there the same space, but the gaseous particles, the molecules, are not conceived to interact with each other.
Of course, there is no such beast as an Ideal Gas. But real gases, at moderate to higher temperatures, and moderately low pressures, approximate the behaviour of Ideal Gases.