Harpies like to search the deck with Harpie Queen for Harpies Hunting Ground, with Hysteric Sign for Elegant Egotist, and for monsters with Harpie Harpist
Mirror Gallery was the first card that basically turned the legend rule off so that you can own multiple copies of the same legendary card at the same time (just like non-ledgendary cards)
Building these decks requires a lot of estimation and educated guesses considering in pretty much every single case, one full on-screen duel is not nearly enough to show their entire deck
The effects of Blue-Eyes Spirit Dragon not being once-per-turn means it can bring out the boss monsters like Blue-Eyes Ultimate Spirit Dragon and Stardust Sifr Divine Dragon with ease
For the time being, if it's within B and F, it's a design that can be obtained by using Azusa as a material, but there are no restrictions on S materials, so it's possible to use WW gimmicks
Dragon , Red-Eyes Fusion , Predaplant Verte Anaconda ) in either the Main Deck or Side Deck, or using Muddy Mudragon to Special Summon Red-Eyes Dark Dragoon to complement their strategy