Since Generation 6, Defog has been buffed to remove all entry hazards from both sides of the field, meaning it is a powerful version of hazard removal that cannot be blocked by Ghost types. Defog is mostly used on defensive Pokemon like Corviknight and Landorus-T to clear hazards for their teammates, and Defog users value longetivity a lot more than Rapid Spin users. However, faster users such as Scarf Kartana and Scarf Landorus-T provide a blend of power, speed, and utility, allowing them to remove hazards before the opposing Pokemon can attack.
Defog is mostly used on slower paced teams or teams that have teammates who would really appreciate the removal of hazards. Slower paced teams can afford to fit the aforementioned bulk Defoggers on their team, and teammates like Mega Charizard Y appreciate teammates that can reliably remove hazards without risking being blocked by a Ghost type. In contrast, teams that use hazards of their own generally slot on an offensive Rapid Spinner if they desire hazard removal; if they were to have a Defogger, their own hazards will also be removed, which is undesired.
Defog also removes Light Screen, Reflect, and Aurora Veil from the opponent's side of the field as well as any active terrain since Generation 8. However, those are less utilized than its hazard removal.
