Crap, sorry. :| Stuff came up yesterday so I couldn't get online.
Well, Swellow might be UU, but it still hits like a truck. A Brave Bird (assuming max attack with Jolly) while Swellow is poisoned will be a guaranteed OHKO on Froslass if it doesn't have any EVs in defense. Actually, thanks to its ability, it effectively has 127.5 base attack. 125 base speed is enough to outspeed every single non-Uber Pokemon except Ninjask (who can't really do much, as the two Ninjasks' strongest move, Aerial Ace, will do 57.5% damage at most), Electrode and Jolteon, who are both OHKO'd by Facade or completely walled by Garchomp (even the Exploding Electrode will do a maximum of 71% damage), Crobat, only one of which poses a problem (the one with the Razor Claw and Brave Bird, as that will have a chance of OHKOing Swellow. The Hypnosis one doesn't pose a problem because you'll already be statused), and Aerodactyl. Aerodactyl will likely be the only Pokemon that'll give you trouble, since Swellow can't do much and it can outspeed and OHKO Starmie. Garchomp can come in, take any hit, and revenge kill, though. There's only one Aerodactyl set that can OHKO Garchomp (Ice Fang), and that only has a chance to.
Conveniently, no Pokemon (in terms of speed) between Swellow and Starmie are Rock-typed, and Swellow can OHKO them all with Facade. You don't have to risk a speed tie with Weavile, because none are maxed out in speed. The reason why Swellow is in UU is because of its lack of coverage - it has no way to scratch Steel or Rock types, but that's what you have Starmie and Garchomp for. ...oh, and conveniently, none of the Jolteon have maxed speed, so Swellow can outspeed those, too, apparently. Of course, some of the EV spreads may be wrong, but...!
... phew. Wasn't planning for this to become that long. xD