Where can I find level ups in Pokemon Diamond?

ok well there is no such thing as a "level up" in Pokemon. you can "level up" a Pokemon by battleing and winning, but you can't find a "level up". but there is a such thing as a rare candy. a rare candy levels up your Pokemon up by one, for example: If your Pokemon was level 63 and you used a rare candy on it it would become level 64 instantly. there are about 5 rare candies in various areas, and i am not sure where those areas are because i forgot. but there are unlimited rare candies you can get at the battle tower. you can't access the battle tower unless you have beat the elite four. at the battle tower you battle and get battle points and rare candies there cost 48 battle points, and it takes a while to get that much battle points because every 7 battles you get only 3 battle points.