This set is designed to actually take advantage of Lunatone's many weaknesses; Lunatone can lure out specific counters, use Rock Polish on the switch, and then proceed to Baton Pass to the appropriate teammate. The last two attacks allow Lunatone to deal decent damage off its respectable base 95 Special Attack stat. With the lack of a good Rock-type STAB, Psychic is the STAB move to use, striking Poison- and Fighting-types for solid damage. Calm Mind gives Lunatone another boost to Baton Pass to its teammates. In most situations, Lunatone will only be able to set up a Rock Polish before needing to Baton Pass out; however, in a Baton Pass chain, Lunatone could be passed some defensive boosts, allowing it to find more time to set up a few Calm Minds before passing to a receiver. Finally, Substitute can be abused in the last slot to bring Lunatone down to a low enough HP total to activate Petaya Berry. Substitute itself can be passed too, and it is very helpful for blocking unexpected status attacks and protecting Lunatone's teammates as it Baton Passes to them.
The EVs are designed to allow Lunatone to reach a Speed stat of 233, enough to just outpace max Speed Torterra. After a Rock Polish boost, Lunatone reaches a Speed stat of 466, enough to outspeed Timid Choice Scarf Rotom. The rest of the EVs are placed into HP and Special Defense to give Lunatone some bulk. Lunatone isn't just limited to passing a Petaya Berry boost, either; any of the pinch Berries make for a good replacement, depending on the Pokemon Lunatone is planning on passing to. Charge Beam is a good alternative to use in the last slot, as it allows Lunatone to go on the offensive and pass on any boosts it receives to its teammates. Psychic and Electric also have fantastic coverage in the UU tier. Explosion can be used in the last slot too, but Lunatone's low Attack stat means it usually won't be doing much damage, especially without any EV investment. It can be useful for punching a hole in Chansey and Clefable, who otherwise wall Lunatone until the end of days, thus allowing a specially oriented sweeper to come in and clean up.
Because of Lunatone's many weaknesses, there are numerous potential teammates who can make use of Lunatone's boosts while covering its weaknesses. Lunatone tends to draw Water- and Grass-type attacks, especially from the two most common Pokemon of UU, Milotic and Venusaur. Therefore, any partner who can make use of the Speed boost Lunatone provides while eliminating the aforementioned Pokemon makes a great teammate. Life Orb Magmortar or offensive Venusaur can easily come in on Venusaur or Milotic, respectively, while boasting an increase to their average Speed thanks to the Baton Passed Rock Polish from Lunatone. Drapion makes a good partner to Lunatone, covering its Ghost-, Dark-, Bug- and Grass-type weaknesses and enjoying the Speed boosts it provides. As a bonus, Lunatone can easily come in on any Ground-type attacks aimed at Drapion and start the cycle all over again. Some good examples of other Pokemon who appreciate Lunatone's Rock Polishes include Azumarill, Octillery, Cradily, Hariyama, Medicham, and Moltres. Finally, if Lunatone gets a chance to use Calm Mind as well, the aforementioned Octillery and Moltres make even better partners, as they are able to capitalize on the Special Attack boosts to become truly devastating sweepers.