In Castelia City, the far right dock is a person who will ask you what stone you want, I think. Something like that, and you just have to say Fire Stone, or Pansear, or say that you picked Oshawott as your starter.
mijuwott said:A scientist(?) at the nearest dock to the bridge(i think) in Castelia City would give you a fire stone if you chose Pansear as one of the pokemon to evolve,miju.
First things first, catch a Timburr or a Throh/Sawk if you haven't done so already. They're a lot of help. Lenora's Watchog is annoying with Hypnosis and Retaliate, so you should train to at least level 20 to be able to defeat her with some ease. After that, it's up to you.