Hello, this is my Graves ADC Guide.
Feel free to ask questions or tell suggestions. Enjoy

Pros


1. Area of Effect Abilities
Graves' abilities which consist of Buckshot, Smoke Screen, and Collateral Damage consist of area of effect damage. Meaning his presence is teamfights can be very influential if you are able to land those abilities correctly.
2. Relatively Easy to Learn

Graves' is easy to learn because his skillshots are not difficult to hit, he's reliable as an AD carry, and he's not punished when harass (passive + above average base armor). It makes him easy to learn because he doesn't have a very high skill cap, and he a lot of his damage does come from his abilities. Another bonus is that he has Quickdraw which makes him more safe in the laning phase and more forgiving when caught.

3. Very High Burst and Great Sustained DPS

His burst comes from his abilities (mainly Buckshot and Collateral Damage) which deal a great amount of damage within a short time, and his sustained DPS is great combined with Quickdraw which gives him a significant attack speed steroid that is lowered every time you auto attack.

4. Effective During All Phases of the Game (except late-late game)

He's effective during all phases of the game because, he strong as a laner (early game), he's good at teamfighting (primarily mid game) and he's has a great attack speed steroid (intended for late game). He does not have a weak point of the game such as Vayne (early game) or Tristana (mid game). However, in 50 minute games, his 525 range may be detrimental and his burst isn't as effective.

5. Strong Laning Phase & Slightly Durable

Graves laning phase is great because of his passive, True Grit which makes him great for trades, Buckshot has a good range is great for harass, and he has the highest base and level 18 health regeneration in the game, making him more difficult to push out of the lane. He also has a repositioning tool.

---

] Cons

1. No Hard Crowd Control (Stuns, Roots, etc)

He does not have a hard crowd control such as Vayne's when the target is near a wall or Ashe's Enchanted Crystal Arrow The only type of crowd control he has is a 15%-35% slow on Smoke Screen

2. Low Auto Attack Range

Graves sports a 525 auto attack range, which is below average for an AD Carry (normally 550). This is what makes laning against Caitlyn (650 auto attack range) or Varus (575 auto attack range) more difficult. It also makes him teamfighting a little more riskier.

3. Long Cooldowns on Abilities During Early Levels

Buckshot. 12 Sec CD
Smoke Screen. 20 Sec CD
Quickdraw. 20 Sec CD (Can be lowered by auto attack)
Collateral Damage. 100 Sec CD (1 min 40 sec) Those are the all the cooldowns of Graves' abilities starting at level 1. They're relatively high, so try to not miss your skill shots.


4. Mana Hungry Early Game

You can redirect to my "Base Statistics" chapter (8th chapter), where there are mana costs in that chapter. To sum it up, Graves used to have a higher mana pool and lower mana costs on his Buckshot, but eventually those were adjusted to amounts with makes Graves out of mana with repeated use of his abilities. Refrain from frequently using your abilities.

Offensive Tree

Fury 4/4: This gives you 4% attack speed at 4 points, since Graves has the lowest base attack speed out of all AD carries, this can help you with your low base Attack Speed. Synergizes nicely with Quickdraw.
Deadliness 4/4: This gives you .67 AD per level at 4 points, totaling to 12 AD at level 18, which is nice, it gives you some more Attack Damage on top of your runes and Brute Force. Makes your Buckshot and Collateral Damage deal more damage.
Havoc 3/3: This increases damage dealt by 2%, it's not going to be very noticeable, but it's the best in the slot.
Weapon Expertise 1/1: This is great for some late game damage, and all your physical damage including your abilities will utilize the 8% armor penetration. This makes Last Whisper a better choice.
2/2: This gives you 5% more critical damage, it won't be effective early game simply because you don't rush critical strikes early game, but as the game progresses and you start buying your Phantom Dancer and Infinity Edge, this will start kicking in.
Brute Force 3/3: You gain 3 Attack Damage from this mastery at 2 points, it basically allows you to cs better, it allows for more harass and some Buckshot and Collateral Damage scaling.
Frenzy 1/1: This grants 10% attack speed after critically striking for 2 seconds, which is nice, this mastery becomes more active the later the game drags on. Makes stutter stepping with Quickdrawing more useful if you constantly crit. This scales very well with Infinity Edge + Phantom Dancer.
Sunder 3/3: This gives you +5 armor penetration at 3 points, which is more than 1/3rd of how much armor you receive from your runes. It allows for better harass and auto attacking the opposing AD carry.
Executioner 1/1: This increases your damage dealt by 5% when a target is below 50% health, it allows you to execute targets better in the laning phase and teamfights, especially with long range abilities like Buckshot and Collateral Damage.
] General Explanation
Standard AD carry Offensive masteries placement. This mastery tree is a must have for all AD carries! The reason for that is you benefit from all the stats that are given. The other Offensive Masteries is damage intended for Ability Power champions, and Graves certainly doesn't need to completely fill in points for the Defensive and Utility masteries. As an AD carry, you don't need the utility provided from other trees, you want more damage because that's what you're supposed to do. Also, Executioner is huge for your role, because AD carries are excellent at cleaning up in teamfights.
Offensive Tree Alternatives
Butcher: This gives 2 / 4 additional damage if you put 1 / 2 points into it. I don't feel the extra damage to minions in necessary on Graves, you want to bully the enemy AD carry more than actually focus on csing, at least that is what I personally do. Plus Graves is has an easy time clearing waves with Buckshot + Smoke Screen.

Graves' Base Stats

Health: 410 (+84 per level)
Attack damage: 51 (+3.1 er level)
Health regeneration: 5.5 (+0.7 per level)
Attack speed: 0.625 (+2.9% per level)
Mana: 255 (+40 per level)
Armor: 15 (+3.2 per level)
Mana regeneration: 6.75 (+0.7)
Magic resistance: 30
Range: 525
Movement Speed: 330

Graves' base stats are relatively great for AD carry, excelling in Attack Damage and Health Regen (highest out of all AD carries), with Armor, Mana, and Movement Speed being above average while the rest is below average (aside from the obvious magic resistance). (Note: Base stats, not per level). Most of that really contributes towards why he is so good in lane. Especially having the highest base Health Regen, combined with his passive and his above average armor makes him more difficult to force out of lane.

Mana Costs

Looking at Graves' stats, Graves has 295 mana at level 1 with mana regeneration of 7.45. At level 1, Buckshot (assuming you took that ability first) will cost around 1/5 of your mana (60). At level 2, if you level Quickdraw second, two of your abilities will cost 110. And it starts to slowly increase as you level Buckshot and put a level in Smoke Screen, so you have to use your abilities conservatively.

I'll make a little graph of how much mana you get at all the levels, and the cost of all the abilities combined.

Level 1 - Mana: 295 Cost of all the abilities: 60
Level 2 - Mana: 335 Cost: 110
Level 3 - Mana: 375 Cost: 120
Level 4 - Mana: 415 Cost: 190
Level 5 - Mana: 455 Cost: 200
Level 6 - Mana: 495 Cost: 300

Yeah, it's pretty hefty if you use all your abilities together, try to use it conservatively, such as only Buckshotting and Quickdrawing in the laning phase and Smoke Screening when you really want to disengage or zone an area. I personally think Smoke Screen at level 1 shouldn't really ever be used offensively as it costs too much mana, only if it guarantees a kill or the person has to literally walk out of the Smoke Screen after the enemy has been initiated on.


Base Damage of Skills


So this sub-chapter section thing, is used to calculate how much damage you can do (base, not with scaling as that has too much variables).

At level 1, a Buckshot will deal 60 damage (assuming you're not up close) + an auto attack with my suggested Runes and masteries will be 73 damage. In total, that it 133 physical damage not factoring resistances. If you execute the auto attack + Buckshot combo early, it will deal at least 90 damage, which is probably at least 1/5-1/6 of their health early game at level 1.

I suggest not using Buckshot at level 2 to harass, and saving mana until level 3, where a lot more burst comes in, same thing with 5.

At level 6 however, it goes from Buckshot and Smoke Screen dealing 190 mixed damage to 440 mixed damage with Collateral Damage. If you wait another level, it can be up to 475 damage, and if you ignite it will deal 665 damage, that is at least half of the enemy AD carry's HP, and that's not even combined with auto attacking or possible scaling.

So, you have a really high potential at level 7 to start killing. That's personally where I start to take advantage of the lane.
Level 1: 60 + 73 = 133 + 0.8 Bonus AD (Auto Attack + Buckshot)

Level 3: 80 + 95 = 175 + 0.8 Bonus AD (Auto Attack + Buckshot)

Level 5: 87 + 130 = 217 + 0.8 Bonus AD (Auto Attack + Buckshot)

Level 6: 130 + 250 + 60 = 440 + 2.2 Bonus AD (Buckshot + Collateral Damage + Smoke Screen)

Level 7: 165 + 250 + 60 + 190 = 665 + 2.2 Bonus AD (Buckshot + Collateral Damage + Smoke Screen + Ignite)

Additional Damage from Buckshot is not calculated, initial damage and scaling from Collateral Damage is used.