Calm Zapdos can switch-in on the three, inspirated additions that now constantly appear since the Diamond/Pearl to Platinum transistion. Those are as follows: Heatran, Skymin and Scizor. Of course, Stealth Rock has been ignored when discussing these scenarios. I tend to lead off with a Deoxys-S that Taunts the suicude lead, and have Starmie waiting in the wings to Rapid Spin the successfully executed Stealth Rock that was not intended.
Fire Blast from a Hasty/Naive/Timid Heatran is unable to 2HKO Zapdos, allowing Zapdos to Roost off the damage, additionally pressurizing Fire Blasts so the opponent has only 4 chances to attack with it. If they explode, then... well, there's nothing you can do about it.
Scizor's attacks, not including Pursuit or Quick Attack, are resisted thanks to Zapdos' typing. Furthermore, Scizor cannot stall Zapdos' Thunderbolts with Roost anymore, as Zapdos now carries Heat Wave for the OHKO; therefore Scizor cannot Swords Dance up and Roost off the Thunderbolts, as it was once capable of doing.
Skymin's Life Orb Seed Flare, one that is successful at reducing Zapdos Special Defense by two stages, and Hidden Power Ice will acomplish the unexpected; eliminating Zapdos, no contest. But I'm sure we're all aware of the Leech Seed varients that many players tend to chose before the offensively-based set I mentioned, which, of course, Zapdos can withstand and can phaze with Roar. In addition, Leech Seed's PP is devided into two, thanks to Zapdos' trait, Pressure.