Speaking of Alakazam, here's a lead set that I'm using right now that works wonders. It easily gets momentum going against the other team by beating most leads (it doesn't stop rocks from going up, though, so have a spinner handy or no weaknesses).
Alakazam@Focus Sash/Expert Belt
Timid Inner Focus
252Spe/4HP/252SpA
-Psychic
-Thunderwave/Taunt
-Signal Beam
-Protect
Psychic is for STAB, and also helps take out Machamp leads and some others in particular, Signal Beam nets the 2HKO on Azelf and other Psychics and doesn't do too bad damage on Ttar (3HKO on lead, which runs SpD EVs). Thunderwave and Protect really make this set shine, IMO. After you beat the opposing lead, the most common switch-in is either Tyranitar or Scizor. Here you Protect to scout whether they're using Crunch/BP or Pursuit. If it's the latter, then you outspeed(even scarf TTar) and can hit it with Thunderwave and then Signal Beam as you die. If it's the former, it gets you a free switch so Alakazam can come back in late game and spread more status or revenge kill off it's glorious 372 speed. Another option that I haven't tried is Taunt to prevent those leads whom you can't beat from getting up rocks.Inner Focus gives a helpful immunity to flinching, but only really to Fake Out as Zam really can't take a hit. By the way, Skarmory and/or Swampert can come in on all the leads Zam loses to and sets up spikes/SR(bar Heatran if it has HP Grass). Just something to consider.
Here's how it handles some popular leads:
-Psychic, you'll either fall asleep or 2HKO
-A lead it can't beat, switch out to Skarm
-You outspeed with Timid and 2HKO with Signal Beam
-You can outspeed and 2HKO
-You can OHKO 2/3 of the time unless you're using Expert Belt, otherwise 2HKO
-Another lead it can't beat, switch out.
-Psychic only OHKOs 28% of the time with Sash, so expert belt is an acceptable replacement to make the kill all the time
-Psychic is a 3HKO, so switching is best.
-You can 2HKO with Signal Beam literally 99% of the time without Expert Belt. If they choose to attack while Scarfed then you get an easy switch.
-You can 2HKO, but watch out for their switch in case they taunt
-Thunderwave right away and switch out
-Unlike Jirachi, you can 2HKO litterally 0.07% of the time. Switch.
-Psychic or switch.
-Just switch now to Skarm.
Fake Out will not flinch you, allowing you to fire off a Psychic, but most players are not stupid and will probably set up SR anyway. 2HKO
You can either Thunderwave it and hope it runs LO(usually does), or you could switch. Psychic also has a good chance of 2HKOing (72%).
There's also a Toxicroak lead I was wondering about that uses Fake Out followed by Me First to KO lead Champ and stuff, which I might post some other time. :P