Persian

Persian@Expert Belt/Life Orb Darkfire/ Alistair
Jolly/Adamant
252 Atk, 252 Spd, 6 HP/ Technician

U-Turn
Faint Attack/Shadow Claw
Fake Out
Aerial Ace

Expert Belt since you're going to hit alot of things SE with the basic set, and IMO Persian is too frail to effectively use Life Orb. 252 Spd EVs with Jolly lets you outspeed or draw with Infernape/Froslass/Gengar/Azelf/Ambipom/Floatzel/Manetric /Espeon/Jumpluff/Tauros and Starmie providing they're not wearing Choice Scarf (i'd say Garchomp aswell but the majority are wearing Scarf). Persians attack isn't great so putting 252 into Atk is usually a good idea. Shadow Claw is also a viable option, it's best to go with Faint Attack over Night Slash since technician boosts FAttack to 90 whilst Night Slash stays at 70; although if you wish to risk the power for a Crit.Hit ratio then go for it.

ICanBeSpecial Persian@Life Orb/Choice Specs/Leftovers Alistair
Timid/Modest
252 Spd/ 252 Sp.Atk/6 HP

Thunderbolt
Shadow ball
Dark Pulse/Nasty Plot/ Power Gem/ Payback
Hidden Power Ice 70

The Persian special set. Obviously if you're going to opt for Nasty Plot, then Specs are a definite no-go. Payback isn't really recommended since there isn't alot that'll outspeed you if you're Timid. Power Gem offers some alternative type coverage and willl be difficult to predict. Persian's Sp.Atk is only 10 lower than it's Atk, so going for the special is an option especially with acess to Nasty Plot however again be aware that Life Orb is going to damage your chances of staying in long enough to set up, which is why Leftovers is worth considering.

Counters

In terms of counters, it really depends on the tier. In BL and Below the only things that outspeed Persian are Sceptile, Electrode and Swellow so that's quite good, your main counters in this tier are going to be things like Azumarill which will take most of your hits and hit back with a SE Focus Punch. Alot of bulky sweepers will stop Persian in all tiers, so using it as a lead with U-Turn and Fake out is useful

Alternatives

Ambipom really does what Persian does ....but better, hence its higher tier.