Hippowdon counters pretty much every Jirachi set, even with sp.def it can beat Calm Mind with Roar.
Edit: Magnezone in the Rain can counter any physical Rachi set with Charge Beam. It occasionally gets lucky with boosts and can KO CM Rachi as well.
Originally Posted by Fat Shurtugal
At +2, Thunder is a OHKO while thunderbolt is doing 87%. I think its safe to say that thundurus-T is exactly what I said: a check.
Only if you're using Life Orb can you KO, and if you are Body Slam can Paralyze you with two chances (since apparently you're switching in Thund-T and Nasty Plotting). If you're using Lum Modest Thund-T has a very small chance of OHKOing at +2.
+2 252+ SpA Thundurus-T Thunder vs. 252 HP / 224+ SpD Jirachi: 343-405 (84.9 - 100.24%) -- 6.25% chance to OHKO
It would take a lot of balls to try and set up on a pokemon who can cripple your sweep.