Well, here's how you EV train in Platinum:
HP: I ev train for hp on the route with that move tutor guy that teaches your pokes the elemental punches and trick, and I ALWAYS seem to run into wild tentacool there too which WRAPS the pokemon I switch into to run away from them, then I have to catch them since I don't want their stupid SpDef EVs
Atk: easy enough, just fish in the water in twinleaf
def: ruin maniac cave, geodudes
SpA: golducks in resort area
SpD: can't remember, haven't EV trained for SpDef in ages
Spe: poliwhirls and poliwags on the freaking sandstorm route which makes it take ages because of the stupid sandstorm thing
so yeah, EV training in Pt is a pain in the ass, which makes me use like one hour EV training one stat. -.-
my entire list of EV trained pokemon in Pt: Azelf, Jirachi, Metagross, Giratina, Metagross (I think, don't ask me why I have two), Rotom, Porygon-Z (I think), Froslass (I think I EV trained it), Typhlosion, Empoleon, Togekiss (i'm not sure if I ev trained it right tho), Jirachi (I have one special and one physical), Dialga, Swampert, Breloom (I think), TTar, Gliscor, Scizor, Scizor (one for legendaries catching, one for competitive use), Darkrai (I think I ev trained it), Infernape, Tentacruel (not mine, but I know it's EV trained), Ambipom (my friend ruined it though, so I need to get a new one [he deleted fake out]), togekiss (yea I have two of them, one T-Wave+Roost and one scarf), Machamp, Starmie (I think), Gallade (not sure if it's ev trained really), Salamence (Not mine, but I know it's ev trained) and that's pretty much it.
Not really that impressive but oh well. xD