In Pokemon Black, the best place to train Pokemon at level 40 and above is Victory Road. Victory Road is a challenging cave located towards the end of the game, filled with high-level wild Pokemon and trainers to battle. The diverse range of Pokemon species and the high experience yield make it an ideal location for leveling up your team before taking on the Elite Four. Additionally, using the Lucky Egg item to boost experience gained can further expedite the training process.
Personally, I would train a Bird-Type Pokemon at a place where those types of Pokemon is very effective to it. Like Fighting-Types. They are weak to Bird-Types. So, I would train it there!
You can not find them you can only train them to 50.
if your pokemon is level 45 and over and you would like to train it go to the elite four and get to the guy or girl your pokemon is super effective on then battle it .
Level 50. Don't train traded Pokemon past level 50 or they won't obey you.
weenboob
At the Pokemon league.
Train it to level 40.
Victory Road.
The best place is probably in victory road or the route before it because of the high level Pokemon and if your asking there is no v.s seeker in Pokemon black an white
find a place that has wild Pokemon the same level as it.
route 205 for Pokemon diamond, pearl and platinum. the trainers have Pokemon from level 10 to level 17
victory road
it depends what level they are. if its not strong enough to battle, give it exp share and go to the league to battle with a stronger pokemon. or if its level is 30 - 40, battle at route 7 where it looks like this
The best place to train Pokemon level 40 and above is at Mt. Silver. Since you cannot gain experience through multiplayer battling, the highest leveled place is Mt. Silver. Pokemon average level 40-49 in Mt. Silver, so it is a good place to train.
Pokemon league :P
elite 4
Nowhere.