My initial run-through of the game, which I completed last week, was done with only an ev-trained modest Empoleon. I cleared the Champion when Empoleon was at lv.84, then I proceeded to complete the sinnoh dex and catch several of the newly available legendaries. After that, I explored the battle frontier island, and began to chain Togepi to find one that would make a successful Togekiss (I have a special sweeper Togekiss on my team in Diamond and Pearl; it's my signature pokémon). The chain finally failed at 29, and I went back to the pc to find the best of the crop. The best I found was a Rash, serene grace togepi with these IVs: 13/28/31/28/1/22. I was very satisfied with this result, and I ev-trained Togepi in Special Attack and Speed. Once Togepi finally evolved, I used the shiny stone to get Togekiss and completed the final moveset of my signature Togekiss. So far, I only have ev-trained 2 team members in Platinum, but I may end up not training a full team of 6, and just using some of my fully ev-trained team members from D&P. Here is my current team:
Togekiss (no item) LV.76
Serene Grace, Rash Nature
6 HP/252 Sp. Atk/ 252 Spd
Air Slash
Aura Sphere
Shadow Ball
Flamethrower
Empoleon (no item) LV.98
Modest Nature
6 HP/ 252 Sp. Atk/ 252 Spd
Flash Cannon
Grass Knot
Hydro Pump
Brine (probably changing this move soon)