Personally, I'm most satisfied by seeing one of my 'mons OHKO an opposing 'mon. Stall just aint my thing As such, I tend to stick with mons with huge offensive potential, like:
Gardevoir @ Gardevoirite
Ability: Trace
EVs: 252 Speed, 252 Sp.Atk, 4 HP
Timid Nature
Hyper Voice/Psyshock/Focus Blast/Calm Mind
Gallade @ Galladite
Ability: Justified
EVs: 252 Speed, 252 Atk, 4 HP
Jolly Nature
Swords Dance/Close Combat/Knock Off/Zen Headbutt
(In case you can't tell, I like the Ralts line :3)
But naturally, that Hyper Offense wants suicide leads like:
Froslass @ Focus Sash
Ability: Cursed Body (I'm still waiting for the Hail equivalent of SS, GameFreak)
EVs: 252 Speed, 252 Sp.A, 4 HP
Timid Nature
Spikes/Taunt/Destiny Bond/Ice Beam
They're fairly standard sets for those 'mons, but I think they reflect the sort of style I like playing (also, Voir, Gallade and Froslass are my 3 favourite 'mons, so w/e )