Note: I have put certain team members in a different order to explain the team so just keep that in mind. There is no need to give IVs or levels as they can’t be changed in Champions. There is also no need to mention EVs that are set to 0. I only used simple EV spreads but you may change them if you wish.
Staraptor-Mega @ Staraptite
Ability: Intimidate
EVs: 32 HP / 2 Atk / 32 Spe
Adamant Nature
- Brave Bird
- Close Combat
- Roost
- Protect
This is the centerpiece of your team, so I am keeping it the same except for a bulkier stat investment. A speed boosting nature isn’t that important as Staraptor is naturally fast and you have tailwind on the team.
Typhlosion-Hisui @ Choice Scarf
Ability: Blaze (Frisk in Bo1 CTS)
EVs: 2 HP / 32 SpA / 32 Spe
Modest Nature
- Eruption
- Overheat
- Shadow Ball
- Solar Beam
You were correct when you said this is a good team member on Staraptor centric teams. Solar Beam gives an additional coverage option into matchups such as rain, and is consistent given Sunny Day activates after switches or mega evolutions.
Whimsicott @ Focus Sash
Ability: Prankster
EVs: 2 HP / 32 SpA / 32 Spe
Timid Nature
- Moonblast
- Tailwind
- Sunny Day
- Fake Tears
Whimsicott is the glue that holds your aforementioned offensive core together. Fake Tears can already boost Staraptor, so Tickle is less important. Instead, Sunny Day helps override weather and boosts Typhlosion’s damage in addition to Fake Tears.
Scizor @ Expert Belt
Ability: Technician
EVs: 32 HP / 32 Atk / 2 SpD
Adamant Nature
- Bullet Punch
- Bug Bite
- Swords Dance
- Protect
Your overall core of Staraptor, Typhlosion, and Whimsicott is good, but lacking against certain matchups. Expert Belt Scizor aims to fix certain matchups such as the one against Mega Floette or Farigiraf TR. Swords Dance can be swapped out for Dual Wingbeat for more flexibility but was chosen because it can decimate teams without an answer to Scizor.
Farigiraf @ Sitrus Berry
Ability: Armor Tail
EVs: 32 HP / 2 Def / 32 SpA
Modest Nature
- Twin Beam
- Thunderbolt
- Helping Hand
- Trick Room
Farigiraf is another teammate that really appears based on the matchup. Thunderbolt helps a lot into rain (including Zard-Y rain). Twin Beam is becoming a better choice as more and more Focus Sash Venusaur or Snealser pop up.
Garchomp @ Life Orb
Ability: Rough Skin
EVs: 2 HP / 32 Atk / 32 Spe
Jolly Nature
- Dragon Claw
- Stomping Tantrum
- Rock Slide
- Protect
Garchomp was on the original and remains an effective attacker against common threats such as Zard-Y or opposing Garchomp, outspending them with a jolly nature.
All in all, while Staraptor is not the best mega in Champions, it is seeing an increase in usage. This team is one of the best ways to use it outside of being a secondary mega on sand teams.