I've had to dust-off my ol' calculator and some of my old statistics to really figure out how powerful and scary this thing is. Because of its Priority and speed, Talonflame says "I go first", and the damage it does cannot be underestimated. I'm going to use my old
Skarmcents system for analysis.
Talonflame has 81 base attack. In my Skarmcents math system... Adamant Talonflame has 173.50 Skarmpoints, and Jolly Talonflame has 157.8 Skarmpoints.
Adamant Talonflame +2 Flying Gem STAB Acrobatics:
173.50 * 2 * 1.5 * 1.5 * 110 == 85882.5 -> 73% to 85.8% dmg to "Theoretical 252/252+ Skarmory". That means
everyone that scores less than "85 Skarmcents" is at risk for OHKO. If it weren't for the resist, 252/252+ Zapdos would be OHKOed by this attack.
Adamant Talonflame +2 Life Orb STAB Brave Bird / Flare Blitz:
173.5 * 2 * 1.3 * 1.5 * 120 == 81198 -> 81.198% Skarmcents of damage.
Looking at the Skarmcents chart, 252/252+ Empoleon is at risk for getting OHKOed... quite an impressive feat.
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Fortunately, anyone who can survive +2 Flying Gem STAB Acrobatics and +2 Life Orb Flare Blitz is a counter: Talonflame ain't doing that damage more than once if you're playing correctly. Just look at everyone who scores 86 and above (98 and above with stealth rocks in play), and you've got your list of survivors. 252/252+ Dusknoir is the first survivor of Acrobatics at 86, 252/0 Hippo also survives with a Skarmcents score of 86.
Assuming a Stealth Rocks disadvantage... Gliscor and Slowbro are barely counters at 98 Skarmcents.
I probably should update my skarmcents chart... its really useful when analyzing these new pokemon.
Oh yeah, and Rock Pokemon resist Acrobatics / Flare Blitz. So they only have to hit 43 Skarmcents to serve as a counter... except Talonflame probably will do +2 Steel Wing for coverage.
Adamant Talonflame +2 Life Orb Steel Wing SuperEffective (ie: vs Rock):
173.5 * 2 * 1.3 * 70 * 2 == 63154 -> 63.154 Skarmcents.
Any rock pokemon at 63 Skarmcents or above (68 with Stealth Rocks) serves as a counter.
This thing has the one of the fastest and most powerful priority attack in the game.
Yes, most powerful priority attack period:
252+ Atk Life Orb Talonflame Brave Bird vs. 252 HP / 0 Def Dragonite: 214-253 (55.44 - 65.54%)
252+ Atk Life Orb Arceus-Normal ExtremeSpeed vs. 252 HP / 0 Def Dragonite: 185-218 (47.92 - 56.47%)
Yup. Talonflame Brave Bird is stronger than Extreme-Killer Arceus's ExtremeSpeed. Both have access to Swords Dance for shenanigans.
ExtremeSpeed at +2 priority, Feint is also at +2 priority IIRC. I'm pretty sure Mega Gengar can run Sucker Punch (not that he's very good with it). So there are a few things in this game that can preempt Talonflame.
But not much... not much at all.