If not a legendary Pokemon, then train it at the Battle Frontier.
uh, you cant really can you? battle frontier you get no exp and its a lvl 50 cap. if you have 50+ then its brought back down to 50. you mean the survival area? go to battle grounds. (house on the left of the Pokemon center, your rival should stand outside of it. you can battle him every once in a while. i don't know how often.) and battle the gym leaders. they all in the lvl 60-66 range. random set every day.
look around twinleaf, and by that i mean look in the patches of grass
If you want a good place to level up your pokemon, I highly recommend the Iron Island or the Fuego Ironworks.
route 205 for Pokemon diamond, pearl and platinum. the trainers have Pokemon from level 10 to level 17
No, it's impossible for a legit pokémon to go over level 100.
You train your Pokemon to lvl 100 or you can find some at the battle frontier in the place where you rent Pokemon and select open level in Pokemon platinum
The best place to level up any Pokemon is the Pokemon league.By fighting the elite four at the Pokemon league your Pokemon will level up realy fast.If you have a low level Pokemon,give it an exp share and make a more powerfull Pokemon battle.
Kind of you have to go to the foggy place and run around a lot.
No
no.
No!
its a secret place
dude just try to find it all around and when you go somewhere that you havn't gone maybe the fossil will be there