Picture this: a tiny, adorable Japanese robin grows up to be a peregrine falcon with pyromancy abilities. Got that image firmly in mind? Awesome; now paint it red and add racing stripes. That's Talonflame, national pokedex number 663, the final evolution of Fletchling and Fletchinder, from which it begins evolving at level 35.
Talonflame is a bit of a metagame "OP; please nerf!" meme, at the time of this writeup, and it has been since the release of Pokemon X and Y Versions in October 2013, the "sixth generation" of main series Pokemon games for handheld Nintendo consoles, chiefly the Nintendo 3DS. Talonflame's Hidden Ability, Gale Wings, gives offensive priority for Flying-type attacks, meaning these attacks are able to hit before any other action can be taken in a Pokemon battle, regardless of the Speed stats of the Pokemon in the battle. This meant that Brave Bird, an extremely powerful Flying-type move, could be wielded with impunity against even the fastest opponents, and all of the EVs which normally would go to the Speed stat could now be invested in the Attack (or Special Defense) and HP stats, giving Talonflame better staying power. Talonflame has been the distilled essence of murder, especially among the Smogon Pokemon metagame community, and some even considered it a genuine game-breaker.
That was prior to the November 2016 release of Pokemon Sun and Moon Versions, the seventh generation of games, in which Gale Wings was nerfed dramatically: now priority only activates when Talonflame is at full health, effectively reducing it to a single high-powered action upon switching into battle, before it loses its main advantageous qualities.
For use strictly within the games themselves, separate from the metagame, Talonflame remains a superb Pokemon. It's primary Ability, Flame Body, is useful for hatching Pokemon eggs, and it still naturally outspeeds most other Pokemon it encounters. It is available almost immediately in X and Y, and in Sun and Moon it is obtainable on Akala Island, which is slightly earlier than halfway into the game; early availability gives the player more time to take advantage of its effectiveness and to train it to an adequate level for facing the endgame.
I, for one, adore Talonflame, even post-nerfing. If six-year-old me had been told, "Someday there will be a fire-type falcon Pokemon with a cheesy name, and it evolves from the most adorable first-stage bird Pokemon in the entire series," I would've been completely stoked about it: this is exactly the type of Pokemon I'd always wanted to have. I would have put my starter Pokemon aside and said "gimme that one; I wanna' do a solo run with it!"
Iron Noder 2016, 16/30