Well, like Dragontamer mentioned, the generally acceptable NFE pokemon are:
-Scyther
-Magmar
-Electabuzz
-Trapinch
-Poliwhirl
-Clamperl
-Vigoroth
-Pikachu
Personally, I wouldn't get annoyed for using Tangela, as the whole NFE issue really hasn't been decided yet anyways. Nor have the tiers of UU/BL, for that matter.
Anyways, about the pokemon we're discussing...
Leafeon: compared to Scyther, it's a much better Baton Passer (lower speed, but much better defense, better typing, and better support moves like Roar/Grasswhistle/Wish), but poses less of a sweeping threat...it deserves some thought since it's not all that difficult to kill, but I'm leaning towards BL. Could use testing, though.
Hitmonlee: Not quite sure. If Claydol comes down, it's most likely safe (Jolly CB Blaze kick does 28.70% - 33.64% to a 252/252 Bold Claydol, unless I miscalculated), and it's pretty fragile too.
Swellow: I already mentioned it, but it's walled to hell and back by Rock/Steel types and is beaten up badly by SR/any priority attack considering it's SR weak and has just plain awful 60/60/50 defenses, not to mention the health it'll be losing from Burn. Fine for UU IMO.
Empoleon: Eh...it can beat up most special walls pretty badly (max/max Calm Grumpig takes 46.43% - 54.67% from LO Surf while Hypno takes 43.58% - 51.34%). Lanturn (resists Surf/Ice Beam and takes very little from Grass Knot IIRC, can hit back with T-bolt), Mantine (huge sp def, resists surf, takes little from Grass Knot, though it needs HP Electric to threaten Empoleon), and Poliwrath (Can't remember how much he takes from grass knot, but if it's not much he could work) could be considered counters. Actually, does anyone have that Grass Knot damage table? I forgot where to find it >_>