My current team in Diamond:
Empoleon / Honchkrow / Skuntank / Lopunny / Luxray / Rapidash
Theme? I may be in a big trouble if there's an opponent that can use Earthquake and is a part of Rock or/and Steel? Is that a theme? 'xD Well, I like all the team members and each of them has a type that nodoby else in the team has (though, both Skuntank and Honchkrow are part of Dark-type). Also, I think my team is pretty girlish - after all, it is based on Platina's team with a few adds. Yup, girlish is my theme.
Empoleon is my starter so that's why it is in my team. Honchkrow, Skuntank, Lopunny and Rapidash are Pokémon that I have wanted to have in my team for a long time and so they ended up being a part of my team. I didn't want to have a Luxray once again, but before I could even notice, I had captured a Shinx (because they just are so cute) and evolved it into a very helpful Luxio.