Those of you in the audience who play a lot of pickleball know all about Pickleball Central.
Obviously, "Paddles" are a Dominant category. It's the primary reason you'd visit Pickleball Central. Some of us churn through a paddle every six months, +/-, some of us collect a hundred paddles and use three of them. Regardless, paddles are the reason you visit the website.
Balls are a Complementary category. If you don't belong to a club, you'll buy balls every few months.
Nets are an Auxiliary category. You don't buy pickleball nets every few months.
Sets & Bundles often serve a dual purpose ... beginners purchase here, meaning that they serve as a Welcome Category in Customer Development terms, and then they are a gateway into other categories.
Shoes are likely to be a Complementary category. So are Accessories.
Clothes are likely a Dominant category - everybody likes to look a certain way on the court, and here in Arizona you'll churn through clothes quickly in 100 degree 9:00am heat.
Gifts likely fall into an Auxiliary category, for obvious reasons.
I don't have the data to analyze Pickleball Central (hint ... hint ... new client opportunity), but those are my guesses.
So as a marketer, you focus on Paddles and Apparel ... your email marketing activities center on those categories. Then you look at the products that are complementary and feature those periodically based on prior purchase preference. Align the products with customer life cycle preferences (i.e. know what a customer with 10 life-to-date purchases buys vs. a first-time buyer) and you have something actionable.