There are a total of eighteen Pokémon types within the Pokémon series, all with their own set of weaknesses and resistances. These weaknesses can be mitigated by a Pokémon's Defense and Special Defense stats, as well as their HP. Water-types are among the most defensive types of Pokémon, having only 2 weaknesses and 4 resistances. Rock-types, on the other hand, have some of the highest defense, 4 weaknesses, and 4 resistances.
Offensively, Rock-type moves are super-effective against 4 types, and Water-type moves are super-effective against 3. Things are pretty even between the two, but there are a few Rock-type moves that prove that Rock is the best typing, while Water-types also have their share of useful moves.
10 ROCK: Stealth Rock Is One Of The Best Entry Hazard Moves
Entry Hazards are moves set by a Pokémon that affect any foe that comes out on a switch-in. Spikes, a Ground-type move, sets up one to three layers of caltrops to inflict 1/8, 1/6, or 1/4 of a Pokémon's health as long as they don't have Levitate or aren't a Flying-type. Stealth Rock, however, is a one-time set-up that, unless it's resisted, will consistently deal damage equal to 1/8 of a Pokémon's HP. If it's super-effective, this increases to 1/4 and if it's quad-effective, this brings it to 1/2. It's arguably better than Spikes because it checks typing in order to do damage, and it requires just one turn instead of 3 for the full effect.
9 WATER: Soak Turns Any Pokémon Into A Water-Type
Utility is important for Pokémon status moves, and Soak is versatile in its usage. Making anything Soak hits into a Water-type means the player can give an opposing Pokémon the two weaknesses of Water to hit for super-effective damage on the subsequent turn. This means that Pokémon on the trainer's team can also be hit in double battles as well.
When paired with typings that have resistances or immunities to electric and grass attacks, this can be a very powerful move. For example, a Pokémon like Lantern could use Soak on a Skarmory to make it Steel/Flying/Water and follow it up with Discharge for x4 super-effective damage.
8 ROCK: Accelerock Is The Quick Attack Of Rock Moves
Priority moves are very important in Pokémon as speed can determine whether or not a Pokémon can sweep or revenge kill successfully. A majority of Rock-type Pokémon are slow, making speed control very important. While some Pokémon with the ability Sturdy can come in and take any one hit and follow it up with an attack move, this isn't ideal as it leaves the Pokémon with only 1 HP. Luckily, Accelerock was introduced in Gen VII as a means of moving first and dealing a nice 40 Base Power of damage. With STAB this is 60, making it an excellent choice for any slower-moving Rock Pokémon.
7 WATER: Bouncing Bubble Can Dish Out Damage While Healing The User
This unique Water-type move is only able to be learned by Eevee from the Let's Go games. It has 90 Base Power and heals Eevee by half of the damage dealt to its target. If this move were to ever be seen outside of this game, it could break the entire meta.
Water Pokémon can be very bulky, and if they ever got an HP draining move, they could have a full arsenal of HP restoring moves with damage output. It's not the only HP-draining move in the game, but it is the one with the highest base power.
6 ROCK: Head Smash Is The Strongest Non-Z-Move Rock Move
With 150 Base Power and 80% Accuracy, Head Smash usually takes out more than 50% of a Pokemon's HP regardless of resistances. It's tied in power with Rock Wrecker, and while the move may sit at 90% Accuracy, the Pokémon has to recharge after it uses it. Head Smash's penalty isn't as harsh, but the Pokémon takes 1/2 the damage it deals as recoil. This can knock it out, but with so many Rock Pokémon having the ability Rock Head, the recoil damage isn't inflicted, keeping them safe from harm. This effectively gives Head Smash no consequences apart from potentially missing the attack.
5 WATER: Water Spout Is A Strong One-Turn Water Move
Tied to the HP stat, Water Spout is incredibly powerful with a catch. The lower the Pokémon's HP that is using the move, the less damage it deals. Compared to moves like Hydro Cannon that require a turn to recharge, this move is preferable if the Pokémon is faster than the opposing mon.
The Pokémon that learn this move aren't especially fast, but when paired up with a Choice Scarf or Trick Room, they can move first and deal an immense amount of damage. Kyogre and Blastoise are the fastest Pokémon that are able to learn this powerful move, and for this is made even more powerful for Kyogre with its high special attack and Drizzle ability.
4 ROCK: Tar Shot Lowers Speed & Increases Fire Attacks
Although it can only be learned by Coalossal, Tar Shot's effectiveness shows off how important speed control is in Pokémon. There are many Pokémon that could benefit from this move, increasing many Rock Pokémon's effectiveness in Double Battles as well. It lowers the target's speed stat, while also making Fire-type attacks super-effective for the duration. Unlike Soak, this move doesn't have as much versatility, but with the speed lowering capabilities, it barely matters. Dropping the target's speed can be perfect for some powerful Fire-type teammates that may be on the slow side.
3 WATER: Fishious Rend Is Perfect For Fast Water-Types
At 85 Base Power, this move can be outclassed by moves like Surf or Hydro Pump, but Fishious Rend is capable of more. If a Pokémon using this move moves before the opposing Pokémon, its damage doubles. At 170 Base Power, this one move does more than every non-signature Z-Move in one hit.
When STAB is taken into account, this move goes up to an extremely high 255 power, and with Rain Dance, this goes to 340. The only catch to this powerful move is that it is only available to two Pokémon. The fossil Pokémon Dracovish and Arctovish from Gen VIII are incredibly slow, but each Pokémon has a Hidden Ability capable of doubling its speed.
2 ROCK: Diamond Storm Raises Defense While Attacking
The signature move of Diancie is the best of both worlds at 100 Base Power and 95% Accuracy. Its strength doesn't just rely on its high base power and high accuracy either. When it connects, the user has a 50% chance to raise its Defense stat by 2x. Considering Diancie's already high 150 Base Power Defense stat, this makes it infinitely more tanky and hard to deal with. If Diamond Storm is ever able to be taught to other Special Attacking Rock Pokémon, there could be a rise in usage of several less popular Pokémon like Probopass and Lunatone.
1 WATER: Scald Is Good For Any Situation
Physical attacking Pokémon are common, and moves that Burn the target are very valuable because of it. Scald has 80 Base Power and 100% Accuracy, capable of moderate damage on anything it hits. Its usage is rarely for offensive purposes, however, as the biggest draw to this move is its ability to burn the target. A 30% chance to burn the target can turn the tides of a battle as burning a Pokémon will halve any damage it deals with physical moves.
Scald can also be used to thaw out Pokémon, making it an excellent counter to the unlikely possibility of being frozen. If a Pokémon is frozen and uses Scald, they thaw themselves out as well. No matter the situation, Scald is perfect for defensive purposes as well as effectively inflicting damage over time on the opponent.