The show focuses on the Russo siblings - Alex, Justin, and Max - competing for the title of family wizard, but there's no specific episode or storyline dedicated to a "wizard competition" amongst the Russos themselves.
The closest thing to a competition would be when Alex, Justin, and Max take turns as "wizard of the week" and compete in various magical challenges. However, this isn't a structured competition with a single winner.
Let me know if you have any other questions about the show!