Alright, so considering you want to take this team online, I'm pretty tempted to say keep the Dragonite, because it's still really good competitively (even with fairies!) but unfortunately, Gardevoir faces a lot of competition from Tapu Lele. Mega Gardevoir can still work though, but that will mean you won't be able to run another mega, and seeing you have Charizard, I'd probably say run the mega on Charizard, and drop Gardevoir for Tapu Lele. As for the rest of your team, I could suggest the following movesets for some of your team members:
Dragonite @ Lum Berry
Ability: Multiscale
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Dragon Dance
- Outrage
- Earthquake
- Extreme Speed/Thunder Punch
Charizard @ Charizardite Y
Ability: Blaze
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Flamethrower
- Solar Beam
- Focus Blast
- Roost
Primarina @ Choice Specs
Ability: Torrent
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Hydro Pump
- Moonblast
- Psychic
- Ice Beam
These three can work rather well together, removing and crippling several walls to allow Dragonite to start sweeping. I know you also have Giratina, and despite having a higher BST than Dragonite, its role is more of a defensive wall and spinblocker (someone that is immune to Rapid Spin) compared to Dragonite. And as for Muk, though, he can help settle any grudges Dragonite has with fairies by threatening them out. Here's a good set that takes on fairies well while also scaring them away:
Muk-Alola @ Assault Vest
Ability: Poison Touch
EVs: 252 HP / 80 Atk / 176 SpD
Adamant Nature
- Pursuit
- Knock Off
- Poison Jab
- Shadow Sneak