I get a real buzz thinking about how 'Supreme King Z-ARC' shows up in duels, so here’s the meat-and-potatoes breakdown I use when building a Z-ARC-ish package.
The central card, of course, is 'Supreme King Z-ARC' itself — the big Fusion/finish that most lists are built around. Around it live the 'Supreme King' Pendulum monsters: the set of dark/dragon Pendulum pieces that feed Z-ARC’s summoning routes and reclaim board presence. You’ll also find 'Supreme King' support spells/traps that enable scale manipulation and recursion, which is what really makes the archetype tick in a match.
Beyond the archetype, typical gameplay involves generic Pendulum and Fusion support: things like 'Pendulum Call' and fusion tools (think classic fusion spells or recursion engines) plus staple search and draw to get pieces. Players also sling in extra-deck dragons and cards that mimic the anime combos (Odd-Eyes/Stardust/Clear Wing-style dragons) as stepping stones to the final form. For me, the fun is in juggling the pendulum scales until I can drop Z-ARC and watch the table tilt — it still gives me chills every time.