If your existing sprinkler controller is mounted outdoors, and you would like to replace it with Wyze Sprinkler Controller, then yes you will need Wyze Weatherproof Sprinkler Controller Box.
Wyze Weatherproof Sprinkler Controller Box is IP65 Waterproof. IP65 requires full protection from dust, oil, and other non-corrosive material, and full protection from contact with enclosed equipment.
Can I use Wyze Sprinkler Controller Weatherproof Box with a different brand of sprinkler controller?
While you may use the weatherproof box with other brands of sprinkler controllers, the box is designed for installing a Wyze Sprinkler Controller. Thus, any attachment method inside will be up to your discretion.