Okay, here we go.
Your team composition looks okay, but there are a few problems. First, most of your team is resisted by Dragon, and Gardevoir isn't the best Fairy type for dragon slaying. You do have the makings of a Fire/Water/Grass core, but for that type of team to be successful, you need a Fairy type or a Steel type, preferably both. Also, your team is mostly made of attackers, yet it doesn't fit into the Hyper-Offensive archetype well. You should add some bulkier Pokemon. Here are some that I think could fit well onto your team:
Alomomola @ Rocky Helmet
Ability: Regenerator
Tera Type: Grass
EVs: 4 HP / 252 Def / 252 SpD
Sassy Nature
- Flip Turn
- Wish
- Scald
- Protect
Dondozo @ Leftovers
Ability: Unaware
Tera Type: Grass
EVs: 252 HP / 4 Atk / 252 SpD
Careful Nature
- Wave Crash
- Curse
- Rest
- Sleep Talk
I would recommend slotting one of these over Samurott-H, as you don't want too many water types, and Ceaseless Edge + Court Change is not a great idea. Also you should rework Ting-Lu to be more defensive. More on that later.
Now, let's go through each team member.
Cinderace
Recommended set:
Cinderace @ Heavy-Duty Boots
Ability: Libero
Tera Type: Grass
EVs: 4 HP / 252 Atk / 252 Spe
Jolly Nature
- Court Change
- Pyro Ball
- High Jump Kick
- U-turn
EVs have been fixed. Max speed so you can Court Change before you die. Bulky Cinderace is not generally a good idea, and I don't even know what you were thinking with the Spa EVs. Boots are so you don't get chipped by the hazards you're trying to remove, and Webs exist, so that too. Temper Flare activates if a move fails, not misses, and it's not that good anyway. U-turn will help keep momentum, and let you switch and deal some damage after you Court Change. Tera Grass resists 2 of his weaknesses and is neutral on the third.
Iron Hands
Recommended set:
Iron Hands @ Assault Vest
Ability: Quark Drive
Tera Type: Flying
EVs: 252 HP / 252 Atk / 4 Def
Adamant Nature
- Drain Punch
- Supercell Slam
- Ice Punch
- Volt Switch
I'm not a fan of Booster Energy Iron Hands. Just because it has Protosynthesis/Quark Drive doesn't mean Booster Energy is the best item for it. AV Hands is much better in my opinion. Drain Punch is better than CC on a bulky Fighting type. You don't need Brick Break to deal with screens, because you have Court Change, which is better. Ice Punch adds the classic BoltBeam coverage. Tera Flying is for ground immunity.
Ting-Lu
Recommended set:
Ting-Lu @ Leftovers
Ability: Vessel of Ruin
Tera Type: Ghost
EVs: 252 HP / 252 Atk / 4 Def
Adamant Nature
- Earthquake
- Ruination
- Whirlwind
- Taunt/Throat Chop
Ting-Lu @ Leftovers
Ability: Vessel of Ruin
Tera Type: Water
EVs: 252 HP / 4 Def / 252 SpD
Careful Nature
- Earthquake
- Rest
- Ruination
- Sleep Talk
The first set is a more offensive Ting-Lu, while the second is a more defensive version. Choose either one, or test to see which one you like better. In both, Stealth Rock is removed, because you have Court Change. Don't shoot yourself in the foot by setting rocks on your side. Lash out is not the best in singles, it's better in doubles where Intimidate is more common. Also I don't know what you mean by "Earthquake for his signature move" because that isn't his signature move, and it doesn't make Ruination better in any way.
Gardevoir
Recommended set:
Don't use Gardevor in Gen 9 OU
If you want a dragon slayer, there are better Fairy types for the job. I have gotten good results with this:
Clefable @ Life Orb
Ability: Magic Guard
Tera Type: Steel
EVs: 252 HP / 4 Def / 252 SpA
Modest Nature
IVs: 0 Atk
- Moonblast
- Ice Beam
- Thunder Wave
- Moonlight
Kills dragons. Check my "What is a good moveset for Clefable" answer to get a more in depth analysis for why this works well.
Samurott-H
Replace with one of the bulky Water types described near the begining.
Electrode-H
Recommended set:
Electrode-Hisui @ Choice Specs/Life Orb
Ability: Aftermath
Tera Type: Dark
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Chloroblast
- Volt Switch
- Thunderbolt
- Foul Play
A Specs or Life Orb set works better, because this Pokémon needs a strength boost to work effectively as an attacker. Air Balloon is usually for those with a Ground weakness. Chloroblast is better because more power is needed than Energy Ball. 4EVs go into Def so you have an odd HP number and can use Chloroblast 3 times. Foul Play uses the opponent's Attack stat, and is great for turning the tables on physical setup sweepers. Volt Switch is for pivoting. Thunderbolt is STAB.
That's all for now. Remember to test your team, and that skill matters too. Having the perfect team (And even with my suggestions this is far from perfect) doesn't mean you will win every time, skill at using it is required too. The best advise I can give is practice makes perfect.
Hope I helped.
