Either Magmortar has a lot more SpA than advertised, or it gets STAB from Tbolt.
[22:52] <Tangerine> Magmortar used Thunderbolt.
[22:52] <Tangerine> It's super effective!
[22:52] <Tangerine> Togekiss lost 102% of its health.
[22:52] <Tangerine> Tangerine's Togekiss fainted.
The guy runs a mild max attack Magmortar (383 max SpA) with Expert Belt.
Togekiss has 368 HP and 282 SpDef.
(42 * 95 * 383 / 50 / 282 + 2) * 2 * 1.2 = 264 max damage, 224 min, meaning there's no way to hit 102% damage (375 damage) on Togekiss...
Perhaps it's calculating STAB?
Also, Resist Berries are used up even if the attack misses. Also, they don't activate on Hidden Power.