Well, I don't really play that rubbish, so I wouldn't know any Doubles Setups regardless.
As a double battles specialist, particularly the rules used in Ranked (which are almost identical to the ones used for VGCs), my recommended hold items are:
- Focus Sash (as Cinderace will likely be targeted for a super-effective move due to its low defenses, and there probably won't be entry hazards)
- White Herb (to give some insurance against Intimidate users)
- Utility Umbrella (to prevent Cinderace's Fire-type moves from being hampered by rain and from residual damage from Sandstorm or Hail)
- Lum Berry (Cinderace's Speed makes it a favorite among anything with Paralysis or Sleep moves)
It may be tempting to put a Passho Berry to help against Rain teams, but the boosted damage from Water-type moves will likely knock Cinderace out in one hit anyway short of a Focus Sash.
These moves are a must on Cinderace, as they work well regardless of partners or circumstances:
- Pyro Ball (an all-purpose signature move)
- Hi Jump Kick (Fighting is super-effective against many types and can easily dispatch Tyranitar while giving Duraludon, Hydreigon, and Snorlax issues)
Depending on what is on the rest of your team and what you might encounter, these moves are quite useful:
- Protect (particularly with Focus Sash--opponents will be itching to take out a Cinderace with 1 HP left)
- Quick Attack (you can never have too much priority in a double battle)
- Iron Head (one way to deal with Togekiss, Sylveon, and Grimmsnarl ASAP)
- Bounce (allows you to waste opponents' Dynamax turns)
- Court Change (steals opponents' Tailwind, Reflect, and Light Screen effects)
- U-Turn (allows you to escape a bad situation, especially if you have someone with Intimidate on your team)
- Substitute (very useful if you find a status-inflicter on the opponent's team, though it won't be useful with Grimmsnarl)
- Gunk Shot (counters Whimsicott, Grimmsnarl, Togekiss, Mow Rotom, and Ludicolo)
- Ally Switch (good if paired with a defensive Pokémon with a lot of resistances)
- Flame Charge or Agility (if you keep finding Dragapult)
- Feint (puts a stop to the opponent's overuse of Protect if you can catch it in time)
- Sucker Punch (put some hurt on Dragapult if it's troubling your teammates)
Regardless of item or moves, the Effort Points spread should be 252 Attack, 252 Speed, and 8 HP. This can also work with 248 Attack, 248 Speed, and 16 HP, since at Level 50, there shouldn't be any difference in stats, though the single point of higher HP will rarely be of any use.
Cinderace's Speed makes it important for you to know the relative Speed of all of your Pokémon. Its effectiveness lies mostly in how well Cinderace can control the battle, and it's most useful when faster than its partner. That being said, Cinderace really appreciates setup created by support Pokémon, and a partner with Quick Guard may be a lifesaver.
Cinderace may or may not be the dedicated Dynamax user on the team. A wide variety of strong physical attacks gives it a lot of options, but there may be something else on your team more dependent on Dynamax, such as Durant or Rhyperior, upon which Cinderace should step aside and let that one do its job. Whatever the case, you should use your best judgment on whom to Dynamax based on your opponent's actions. It would be reckless to use Max Flare if your opponent already uses a sunlight-based team, for instance.
NOTE: I don't actually use Cinderace in battle myself, so these are untested, but I base it off of what I see in competitive double battling and what go-to Pokémon strategies and team-wide strategies are the most popular and/or most effective.