Talonflame- Talonflame is used mostly for a fast Taunt and Tailwind. With +1 Tailwind (assuming that Fake out doesn't break Gale Wings, which is why Protect is a pretty common move for it as well), it makes a great Tailwind setter. With base 126 Speed, it can usually get a Taunt in before the opponent moves, assuming that Prankster is not involved.
Charizard- With Solar Power, Max Flare is pretty dangerous on it. With access to Heat Wave paired with fairly good 106 base Special Attack, it can also get some decent spread damage in (as seen here, Heat Wave is its most common move with 74.8% usage). Of course, it can also be used as a G-Max with a Drought Pokemon next to it, explaining why Ninetales is its most common teammate.
Sneasel- As I explained in my comment, Sneasel has three main niches in VGC: Inner Focus, Surf, and Beat Up. First, it can absorb Fake Out flinches due to Inner Focus, which is one of the most common moves in VGC. Surf has 74.6% usage as far as Sneasel's moves go, which is for basically one reason: Coalossal. With low Special Attack, Surf won't do too much to Coalossal, and it activates both its WP and Steam Engine, explaining why Coalossal is its most common teammate (source). Oh, oops, forgot to elaborate on Beat Up. Beat Up + Justified is probably the main reason why Sneasel is used. Beat Up has 79.1% usage on Sneasel and Cobalion is Sneasel's 2nd most common teammate.
Note: I may be wrong about some of this stuff, I'm pretty terrible at VGC, but this is all from what I understand about the format + the Pikalytics data.
Hope this helps! :)