In my White 2 game, i'm already playing with my dream team. Most other games I try to have a variety to try out different Pokemon, but I always tend to keep at least 2 of my all time favorites.
Dream Team in my White 2 consists of:
• Mienshao - shiny (that I transferred over from Black 2), my favorite of all the fighting types
• Mienshao - since I couldn't get Linoone (when I started the game), I ended up with another one
• Watchog - long time #1 favorite (now its #9), but never missing in any of my Unova teams
• Zangoose - another of my normal-type favorites
• Floatzel - #2 favorite of all times, love this sea otter Pokemon, always have trouble deciding whether to make it evolve from Buizel or not. It learns 3 out of my 4 favorite attacks [can't learn Razor Shell].
• Dewott [with an everstone] - at the moment its my #1 favorite, and so far the only starter I have chosen in Unova, it can never be out of my Unova games (with the exception of my "all cat team" in Black). It learns my top 4 favorite attacks [Razor Shell, Surf, Aqua Jet, and Aqua Tail].