Calm Mind Spoink is a force to be reckoned with once it has set up. After just one Calm Mind boost, Spoink hits 24 Special Attack and 22 Special Defense, meaning it can hit quite hard, while also being able to withstand many special attacks with its above average Special Defense stat. Psychic is Spoink's main attack, gaining STAB, and hitting most opponents quite hard, especially after several Calm Mind boosts. The next slot is used to hit Steel-type Pokemon, who would otherwise wall this set, super effectively. Hidden Power Fighting has great neutral coverage with Psychic, hitting all Pokemon for at least neutral damage bar opposing Psychic-types, and OHKOes Aron, who could otherwise set up a Rock Polish before taking Spoink out with Head Smash. Hidden Power Fire is also an option to hit Steel-types, and hits Bronzor, who does not have much to fear from any of Spoink's other attacks, particularly hard. Finally, Shadow Ball allows Spoink to hit opposing Psychic-type Pokemon for super effective damage. Substitute is also an option instead of Shadow Ball, allowing Spoink to scout for opposing Pokemon, especially Pokemon faster than Spoink, who would otherwise be able to OHKO Spoink before it can switch out or attack.
Spoink has a plethora of items it can run. Oran Berry gives Spoink more longevity, and often allows it to set up another Calm Mind before putting the hurt on its opponents. Life Orb trades longevity for power, making Spoink much easier to knock out, but also much harder to wall. If Substitute is opted for the last slot, Salac Berry becomes an option. With Substitute, Spoink can safely activate Salac Berry, and proceed to outspeed Pokemon who are usually faster than it, and KO them with the appropriate move. However, at 25% health, Spoink becomes very easy to knock out by priority attacks, which are rife in the metagame, and so it is not recommended. The EV spread maximizes Spoink's Special Attack and Speed stats, and increases its HP and Special Defense by one point each. A Timid nature allows Spoink to hit 16 Speed, which is slightly above average. A Modest nature can also be used, trading the ability to outrun certain threats for more power, but is usually not worth it given the extremely fast-paced nature of Little Cup. Thick Fat is again used because being able to take Fire- and Ice-type attacks better are very important for Spoink.
If Spoink lacks Hidden Power Fire in its movepool, Bronzor will have an easy time against Spoink, so Magnemite then becomes a good teammate, thanks to Magnet Pull. Magnemite can trap Bronzor and take it out with a powerful STAB Thunderbolt. With Bronzor eliminated, Spoink will find it much easier to sweep. As an added bonus, Magnemite also resists all of Spoink's weaknesses. If Hidden Power Fire is absent, Aron will be able to set up a Rock Polish against Spoink, and eliminate it with a Head Smash. Therefore, a Bronzor of your own makes a fine teammate, resisting or being immune to any of Aron's attacks, and being able to dispose of Aron with Earthquake.