Usually with an in-game team I try to make mines with a bit of originality and variety. For example, a lot of people who played Diamond and Pearl used Buizel as their water type if they didn't have one already, so instead I chose to use Finneon's line. Seeing as a lot of people are choosing Mareep's line of evolution for their electric type, I might either not choose to have an electric Pokémon in my party, or I would go with a different choice, such as Magnemite's line since I've never trained one before.
I don't know exactly what I'll do in the game for my whole team as I'm leaving it up to relative surprise on what I train this time around, so we'll see...