Sorry for the late reply!
In all honesty, it needs some improvement. It's not bad, it just needs a lot of work. But that's okay, you won't master competitive Pokemon immediately.
So, let me help you out here:
Guzzlord isn't a very good Pokemon, and it doesn't do much for the team. I see why you would use it, and it isn't the most terrible choice out there, I just feel like there are better Dragons. It's not even ranked in the Monotype Viability rankings. (VERY helpful website. You should definitely use it, along with any other monotype resources on the forums, for any monotype team you're building. Seriously, it's a life saver)
I feel like he should instead be replaced by Mega Altaria.
Altaria-Mega @ Altarianite
Ability: Natural Cure
EVs: 248 HP / 8 Atk / 252 Spe
- Dragon Dance
- Heal Bell / Refresh
Mega Altaria is a must-have on Dragon teams, in my opinion. Its Fairy typing makes it extremely useful against other Dragon teams, since it grants you a nice immunity to them. They also have decent bulk and a great ability in Pixilate. This makes Altaria's Return especially powerful with STAB plus a power boost! We also have Dragon Dance to make Altaria a deadly set-up sweeper. Roost and Heal Bell give Altaria some longevity, and Heal Bell also cures your other teammates from status. Heal Bell is especially useful for dealing with walls. Because we have a way to beat wall's statuses, we now need to deal with their attacks. With 248 HP EVs, we now have some bulk that will be harder for opponents to take them out. This means Porygon2 cannot 2HKO us with Ice Beam, and other Dragon teams will struggle to take us out.
You also now have a Mega, so that's good!
Goodra is not the worst Pokemon for a Dragon team, far from it actually, but I still think we can do better.
Instead, we can do Dragagle:
Dragalge @ Poison Barb
EVs: 228 HP / 252 SpA / 28 Spe
IVs: 1 Atk
- Draco Meteor
- Sludge Wave
- Toxic Spikes
- Hidden Power [Fire]
This is your key to helping you in your Fairy matchups. Dragalge has a nice neutrality to Fairy moves, and the Poison Barb combined with Adaptability means that Fairy teams will struggle a lot against this guy. He also provides Toxic Spikes, something no other Dragon can use and something that will make a Fairy team struggle, since they don't usually have hazard removal. Also, him being a Poison type is important because the most common Fairy types are neutral to Steel types due to a secondary typing, so Poison is now even more viable. For Pokemon like Klefki and Magearna, we also have HP Fire for that, which could also be useful against Ferrothorn and Mega Scizor. The maxed out Special Attack with the Modest nature allows Dragalge to hit as hard as possible. The HP EVs give Dragalge some mixed bulk, and 28 Speed EVs allow him to outspeed Hippowdon.
Alolan Exeggutor isn't exactly worth using on a Dragon team. It's better suited for a Trick Room team, and you're not exactly using the best set for it. It would be better to use an Offensive set, like the ones on Smogon.
However, I think you will be better off using Latios.
Latios @ Choice Scarf
EVs: 252 SpA / 4 SpD / 252 Spe
IVs: 0 Atk
- Draco Meteor
- Hidden Power [Steel]
Latios provides Speed control with its Choice Scarf, and removes entry hazards with Defog. Defog is especially important when you have Dragonite on the team, since Stealth Rock breaks Multiscale. It's a fantastic Pokemon for the team, being able to outspeed pretty much every unboosted Pokemon in the tier, as well as some Choice Scarf users like Excadrill and Keldeo. With its strong special attacking power and high speed, it's a very good addition to this team!
Dragonite is a great choice for your team, especially with its ability in Multiscale! However, the EV spread and moves need a lot of work.
There is no need to divide the EVs like that. You should run 252 Atk / 4 Def / 252 Spe EVs, with an Adamant nature. Remember, natures are extremely important!
The moveset here is also a bit odd. You have a mostly special set, when Dragonite is really more of a physical attacker. I think this set will be better:
Dragonite @ Choice Band
EVs: 252 Atk / 4 Def / 252 Spe
- Extreme Speed
- Fire Punch
- Superpower / Earthquake
Choice Band allows for Dragonite to be a fantastic All-Out Attacker. Outrage is great at breaking most walls early-game, but be careful not to lose HP when Multiscale will be important later in the game! Extreme Speed allows for Dragonite to revenge kill, and Fire Punch along with the maxed out Attack, Choice Band, and Adamant nature allows Dragonite to 2HKO Skarmory, who is common on Steel teams that may give you some trouble! The Speed EVs also let Dragonite outspeed Adamant Mega Scizor and Adamant Diggersby. Finally, Superpower breaks the defensive Normal core of Chansey+Porygon2.
Dragonite is a bit of a hard Pokemon to use, so you should probably look at the Smogon page for him, especially in the Usage Tips. There is absolutely nothing wrong with going to Smogon for help, no matter how experienced you are! It's there to help you.
Don't use Gible. Garchomp is superior in every way. Maybe Gible has the benefit of Eviolite, but why not use a defensive Garchomp?
I think there are two spreads that can work with this team:
Set 1: Defensive Stealth Rock
Garchomp @ Rocky Helmet
Ability: Rough Skin
EVs: 252 HP / 16 Def / 148 SpD / 92 Spe
- Stealth Rock
- Fire Blast
Set 2: Focus Sash (my preferred set)
Garchomp @ Focus Sash
Ability: Rough Skin
EVs: 252 Atk / 4 SpA / 252 Spe
- Fire Blast
- Stealth Rock
This will work with your team a lot better!
Finally, I think you should use Kyurem over Salamence.
Kyurem-Black @ Life Orb
EVs: 4 Atk / 252 SpA / 252 Spe
- Ice Beam
- Fusion Bolt
- Earth Power
- Roost / Hidden Power [Fire]
Kyurem is pretty much mandatory on any Dragon team. Its Ice typing makes him take neutral damage to Ice attacks, a typing that can destroy Dragon if you aren't prepared to deal with them. IceBolt coverage is some of the best coverage you can have in the meta, being able to hit pretty much everything at least neutrally. Earth Power is another useful coverage move that can take on Steel teams that would otherwise wall Kyurem. Roost gives Kyurem some longevity and helps deal with LO recoil and entry hazards. For an all out attacker set, you can also use HP Fire, which is the perfect anti-Steel coverage combo. The stats allow Kyurem to hit as hard and fast as possible, and the 4 Attacking EVs help him to boost Fusion Bolt's power.
Good luck with your team! I hope my suggestions helped you out! If you need any more help with monotype, then don't hesitate to ask me! I'm no expert, but I have a basic understanding of the metagame and monotype is my life!