Help building a team

[MarceeNavy]

Hey guys!
After years of playing the games, I finally started to do some more competitive stuff. Unfortunately I lack some knowledge on how to do so.
My first idea is the following:

Corviknight @ Aguav Berry
Ability: Mirror Armor
EVs: 252 HP / 16 Def / 174 SpD / 66 Spe
Impish Nature
- Brave Bird
- Body Press
- Tailwind
- U-turn

Togekiss @ Sitrus Berry
Ability: Serene Grace
EVs: 244 HP / 92 Def / 112 SpD / 60 Spe
Calm Nature
- Dazzling Gleam
- Air Slash
- Follow Me
- Helping Hand

Rotom-Wash @ Heavy-Duty Boots
Ability: Levitate
EVs: 248 HP / 44 SpA / 216 Spe
Timid Nature
IVs: 0 Atk
- Hydro Pump
- Volt Switch
- Will-O-Wisp
- Protect

Excadrill @ Focus Sash
Ability: Mold Breaker
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Iron Head
- Earthquake
- Rock Slide
- Rapid Spin

Arcanine @ Rocky Helmet
Ability: Intimidate
EVs: 252 HP / 42 Def / 68 SpA / 148 Spe
Modest Nature
IVs: 0 Atk
- Flamethrower
- Snarl
- Roar
- Protect

Ferrothorn @ Leftovers
Ability: Iron Barbs
EVs: 252 HP / 252 Def / 4 SpD
Impish Nature
IVs: 0 Spe
- Gyro Ball
- Leech Seed
- Stealth Rock
- Knock Off


So, I lead with Corviknight and Ferrothorn to set up Tailwind and hazards. But fire-types completely destroy me. Even if I switch in to Rotom-W or Arcanine, I don't think I have the coverage to deal with them. From here, I just don't know what to do. I don't even think my team covers the major threats to itself.

I also have these:

Toxapex @ Black Sludge
Ability: Regenerator
EVs: 252 HP / 252 DEF / 4 SpD
Bold Nature
- Scald
- Haze
- Toxic Spikes
- Recover

Dragapult @ Focus Sash
Ability: Infiltrator
EVs: 252 SpA / 252 Spe / 4 SpD
Timid Nature
- Draco Meteor
- Shadow Ball
- Flamethrower
- Thunderbolt

- G-Darmanitan with Zen Mode
- Eiscue with Belly Drum and Icicle Crash

Anyone can help?
Thank you so much :)

 

[Twilight]

I'm locking your RMT for the time being as the forum rules require that you provide at least 3 lines of descriptions for each Pokemon to explain their roles. Please read the rules carefully and take a look at Team Showcase to see the level of detail we require. PM me with updated descriptions and I'll be happy to unlock this.