Updating the Choice Specs set, which I feel does not give the best coverage. I'm also adding a Rest-Talk set, which I have used in my recent stall team to great success.
http://www.smogon.com/dp/pokemon/jirachi
[SET]
name: Choice Specs
move 1: Psychic
move 2: Thunderbolt
move 3: Grass Knot / Hidden Power Ground
move 4: U-turn / Icy Wind
item: Choice Specs
nature: Timid
evs: 80 HP / 252 SpA / 176 Spe
[SET COMMENTS]
<p>This Jirachi is meant to hit hard and fast, though with special attacks, unlike the previous set. Unlike the Calm Mind Sweeper, this requires no set-up, but is also dealt with with much greater ease against defensive teams, as it can't set up a sweep. However, it is also more unexpected.</p>
<p>Psychic is the main STAB attack, hitting many common OU threats such as Infernape, Gengar, Roserade, and Heracross for super-effective damage. Grass Knot hits many common switch-ins hard, such as Tyranitar, Hippowdon, and Swampert, OHKOing the latter and 2HKOing the former two. Thunderbolt hits Skarmory and Forretress reasonably hard, as well as Gyarados, making this an effective Gyarados counter (assuming it lacks Earthquake). The last slot is for a utility move. U-turn is the preffered option, as it scouts the opponent's team, allowing it to run from unfavorable match-ups (such as Bronzong and Blissey), as well as dealing massive damage to Celebi. Icy Wind is to hurt Garchomp on the switch, breaking its Yache Berry to make it easier to counter, or 2HKOing it (with the Speed drop in effect) if it lacks a Yache Berry. It also helps take care of Salamence and Gliscor.</p>
[SET]
name: Rest-Talk
move 1: Rest
move 2: Sleep Talk
move 3: Psychic
move 4: Grass Knot / Thunderbolt
item: Leftovers
nature: Calm
evs: 252 HP / 116 Def / 140 Spe
[SET COMMENTS]
<p>Though Jirachi has access to a perfectly suitable healing move in Wish, Jirachi may choose to forgoe that in favor of the more unreliable Rest-Talk, because Jirachi makes a great switch-in to many common sleep-users such as Roserade, Gengar, and Yanmega due to high defenses and STAB Psychic. The last slot is for type coverage, with Grass Knot hitting Tyranitar, Swampert, and Hippowdon, and Thunderbolt hitting Gyarados and Skarmory.</p>
I didn't really expand much on the Rest-Talker set, but I didn't think there was much to say, really.
http://www.smogon.com/dp/pokemon/jirachi
[SET]
name: Choice Specs
move 1: Psychic
move 2: Thunderbolt
move 3: Grass Knot / Hidden Power Ground
move 4: U-turn / Icy Wind
item: Choice Specs
nature: Timid
evs: 80 HP / 252 SpA / 176 Spe
[SET COMMENTS]
<p>This Jirachi is meant to hit hard and fast, though with special attacks, unlike the previous set. Unlike the Calm Mind Sweeper, this requires no set-up, but is also dealt with with much greater ease against defensive teams, as it can't set up a sweep. However, it is also more unexpected.</p>
<p>Psychic is the main STAB attack, hitting many common OU threats such as Infernape, Gengar, Roserade, and Heracross for super-effective damage. Grass Knot hits many common switch-ins hard, such as Tyranitar, Hippowdon, and Swampert, OHKOing the latter and 2HKOing the former two. Thunderbolt hits Skarmory and Forretress reasonably hard, as well as Gyarados, making this an effective Gyarados counter (assuming it lacks Earthquake). The last slot is for a utility move. U-turn is the preffered option, as it scouts the opponent's team, allowing it to run from unfavorable match-ups (such as Bronzong and Blissey), as well as dealing massive damage to Celebi. Icy Wind is to hurt Garchomp on the switch, breaking its Yache Berry to make it easier to counter, or 2HKOing it (with the Speed drop in effect) if it lacks a Yache Berry. It also helps take care of Salamence and Gliscor.</p>
[SET]
name: Rest-Talk
move 1: Rest
move 2: Sleep Talk
move 3: Psychic
move 4: Grass Knot / Thunderbolt
item: Leftovers
nature: Calm
evs: 252 HP / 116 Def / 140 Spe
[SET COMMENTS]
<p>Though Jirachi has access to a perfectly suitable healing move in Wish, Jirachi may choose to forgoe that in favor of the more unreliable Rest-Talk, because Jirachi makes a great switch-in to many common sleep-users such as Roserade, Gengar, and Yanmega due to high defenses and STAB Psychic. The last slot is for type coverage, with Grass Knot hitting Tyranitar, Swampert, and Hippowdon, and Thunderbolt hitting Gyarados and Skarmory.</p>
I didn't really expand much on the Rest-Talker set, but I didn't think there was much to say, really.