in sunnyshore
The 8th gym leader in Pokemon Light Platinum is located in a city called Lauren. You can find the gym leader in the Lauren League Headquarters.
Roark is the gym leader. You can find him in the mine at the lower end of the town.
The eighth gym leader is Claire in Blackthorn City
You get it when you beat the Galaxy Leader in the Base in Veilstone City. He brings it to you!
in the begging of the game theres a gym near pallet town that's where Giovanni is the last gym leader
You shall have it when you defeat the 7th gym leader
in sunyshore city after you have gone to spear pillair and distortion world
buy the Pokemon platinum book
The 151st Pokemon is Mew and is unobtainable in Pokemon Platinum.
no you can't find a torchic egg in Pokemon platinum
Blue (The eighth gym leader) is waiting on Cinnabar. He won't battle you unless you've beat the rest of the gym leaders
Roark, a Rock-type specializing Gym Leader, can be found in Oreburgh City (just like in Diamond and Pearl).