One of the characteristic aspects of the NU tier is its overall lack of Spikes users, with Cacturne and Garbodor being the only popular candidates for the role. Because of this, Omanyte holds an important niche over other Water-type Pokemon in the tier with its almost-exclusive access to not only Spikes, but also Stealth Rock and Toxic Spikes, making it the most comprehensive hazard supporter in the tier. Furthermore, unlike its aforementioned rivals, Omanyte has extremely impressive physical bulk when equipped with Eviolite, as well as the ability to shut down powerful physical attackers such as Swellow, Braviary, and Skuntank. Unlike most physical walls, it also has respectable attacking power, with great dual STAB types in Water and Rock, in addition to an above-average base 90 Special Attack stat that is useful on both defensive and offensive sets.
However, while Omanyte certainly has a lot of utility within the tier, it also has some highly exploitable weaknesses that make it unsuitable for pure walling. With base 35 Speed, Omanyte will not be able to outspeed even its rival Rock-type Pokemon, Golem and Armaldo, without investment, and thus has to rely almost exclusively on its bulk to respond to offensive Pokemon. In addition, its uninvested Special Defense stat is low even after the boost from Eviolite, and as it is weak to Grass-, Electric-, Fighting-, and Ground-type attacks, opponents will almost certainly have a solid offensive response to Omanyte somewhere on their team. Omanyte also lacks reliable recovery, which means it can be slowly worn down by repeated attacks and status effects over the course of a match. Nevertheless, Omanyte excels at switching into attackers that it walls and setting up hazards or firing off attacks until the opponent switches to a more threatening Pokemon. With excellent physical bulk, good resistances, respectable offensive presence, and access to every hazard in the game, Omanyte is a threat that is both vastly underestimated and surprisingly effective.
Omanyte's access to all entry hazards, ability to use Eviolite, and exceptional Defense stat allow it to excel as a bulky Spikes user on both defensive and offensive teams. This set capitalizes on Omanyte's raw bulk: reaching a ludicrous Defense stat of 492 with full investment, Omanyte can take even super effective physical attacks well. For reference, Swellow's Guts-boosted Facade deals a mere 15.32% - 17.88%, while Choice Scarf Braviary doesn't even 2HKO with Superpower. As Omanyte will take pitiful damage from most neutral physical hits, it finds plenty of opportunities to set up Spikes as opponents switch out, often managing to set up all three layers as opponents struggle to dent its shell. Stealth Rock is more suited to offensive teams, while Toxic Spikes aid stall teams in slowly wearing down bulky opponents; use whichever hazard complements your team the best. Of course, Omanyte can also elect to use both Stealth Rock and Toxic Spikes; while it can feasibly run all three entry hazards on a single set, Omanyte can make better use of its other attacking options most of the time.
Scald is chosen as Omanyte's primary attack as it not only boasts respectable power, but it can also burn physical attackers that attempt to muscle through Omanyte with Fighting- and Ground-type attacks. Furthermore, it is a good move to hit switching opponents with after hazards have been set up. Hidden Power Rock is Omanyte's strongest Rock-type move and lets it OHKO Swellow and 2HKO Braviary, giving it better offensive coverage and ensuring that it isn't as helpless against these foes as its competitors, such as Wartortle, are. On the other hand, Toxic can be used to hit bulky opponents such as Misdreavus which would otherwise be able to set up on Omanyte with ease.Team Options & Additional Comments >>>
While an Eviolite-boosted base 100 Defense stat is one of the main reasons to use Omanyte over other Spikes users, Omanyte's offensive power should not be underestimated: it has the ability to 2HKO a significant proportion of the tier if its opponent isn't careful. The combination of Surf, Hidden Power Rock, and Ice Beam gives Omanyte excellent neutral coverage against the tier, and scores super effective hits against common opponents such as Golem, Braviary, and Regirock, letting Omanyte break through them quickly. Meanwhile, Omanyte can still use Spikes effectively as foes such as Swellow will be forced out regardless. In fact, most opponents will assume Omanyte is using the standard defensive set until it hammers them with its attacks. Some opponents, such as Altaria, will attempt to boost against it as it sets up Spikes, only to be OHKOed by Ice Beam, much to their surprise. This Omanyte can even lure in and KO some of its biggest checks, especially slow, bulky Grass-types such as Vileplume, by 2HKOing them with Ice Beam on the switch-in. Overall, while offensive Omanyte won't be able to take as many hits as the standard set, its ability to hit opponents directly for significant damage gives it more utility on offensive teams that want to place as much pressure on the opponent as possible.Team Options & Additional Comments >>>
Shell Armor is Omanyte's default ability, as it makes Omanyte a more reliable check to physical attackers by ensuring they can't break through it with critical hit. Weak Armor completely negates Omanyte's physical bulk, its main niche over other Spikes users. Furthermore, Omanyte isn't fast enough to capitalize on the Speed boosts, so Weak Armor should never be used. Swift Swim, on the other hand, can be useful if you happen to be using Omanyte on a Rain Dance team; with a small amount of Speed EVs, it can outspeed most defensive Pokemon and set up Spikes against them more easily. Shell Smash also becomes more usable in this scenario, as Omanyte can outspeed most Choice Scarf users after a boost due to Swift Swim, and its main STAB becomes much more powerful. Omanyte can even use Rain Dance itself, as it forces switches against certain opponents quite easily, although you must make the difficult choice between using Eviolite for extra bulk or Damp Rock for more rain turns.
Additionally, Omanyte gets access to Clear Smog and Haze, with which it can try to deal with boosting opponents, but these aren't very effective due to Omanyte's many exploitable weaknesses, low Speed, and lack of recovery. Knock Off is an interesting option that removes opponents' items, but it can be hard to fit into a moveset. AncientPower can be used over Hidden Power Rock if you're feeling lucky, but the latter's higher Base Power and PP make it the more reliable choice in general. Finally, it is worth noting that Omanyte can attempt to alleviate its recovery problems by using a set of Rest, Sleep Talk, Spikes, and Scald; while this has less overall utility than the current defensive set, it's much more self-sufficient. However, it's worth noting that once Omanyte uses Rest, it is likely to stay asleep for the rest of the match, as it is easily forced out.
Checks and Counters
Tentacool, Omanyte's fellow NFE Water-type introduced in RBY, is its largest nemesis. It beats Omanyte in pretty much every scenario, as it takes almost nothing from Omanyte's attacks, is immune to Toxic, can use Rapid Spin to remove Omanyte's Spikes, and can force it out with the threat of Giga Drain. Natu can reflect Spikes with its Magic Bounce ability, as well as use Light Screen and Roost to reduce the damage it takes from Hidden Power Rock while providing dual screens support for its teammates.
More generally, Grass-type Pokemon will almost always beat Omanyte with their 4x super effective STAB attacks and resistance to Water-type moves. Tangela, Torterra, and Leafeon all outrun the offensive set even with uninvested Speed, and can either quickly KO Omanyte with their STAB moves or capitalize on the free turn by setting up in their respective ways. However, they are all hit hard by the offensive set's Ice Beam, and should therefore be careful when switching in. Powerful Volt Switch users such as Rotom-S and Eelektross can deal with Omanyte easily while simultaneously stealing momentum, especially if Omanyte doesn't run Special Defense EVs. Fighting-type Pokemon with the Guts ability can also set up on defensive Omanyte with impunity; Gurdurr fears nothing from Scald and can restore any HP it loses with boosted super effective Drain Punches, and specially defensive variants can shrug off even Hydro Pump.
In general, the defensive set is setup bait for Pokemon such as Shell Smash Gorebyss and Calm Mind Gardevoir, both of which can threaten a sweep by switching into Omanyte as it uses Spikes. Meanwhile, the offensive set is generally beaten by bulky opponents that can hit Omanyte super effectively, such as Throh and Regice; Rapid Spin users can be brought in later to remove Spikes.