For in-game, I might go the nostalgic route and do something similar to the team I had in the original Gold, way back when I was like... ten. xD; In which case it would be something along the lines of:
Typhlosion
Umbreon
Noctowl/Pidgeot
Ampharos/Raichu
Lapras... I think that's what I used. xD; maybe red Gyarados too, since it looks cool :p
maybe Jumpluff for cuteness, or Shuckle because they make me laugh, or Ursaring because it looks awesome... I dunno. xD
So as you can see, I really don't have a strong idea for my in-game team. As for competitive battling... I have even less of an idea! xD; I'm just excited for the games to be released, that's all I can think about. x3