She is found in Sandgem town in the biggest house, I think...
Go to Dawn's little sister, sometimes there are skittys in a Pokemon Breakout.
Try talking to Dawn's sister everyday and if you are lucky you might catch kelcleon.
You talk to Dawn's sister after you get the national pokedex and she will tell you where to catch certain rare pokemon. Sometimes you will get a Phanphy.
She tells you about a wide variety of Pokemon, Pokemon which can only be caught in swarms which occur daily. Talk to her and she will tell you where the swarm is and which Pokemon are in it.
She is in sandgem city (platinum)
you dont see her
Your rival's sister tells you about rare Pokemon appearances. Each day a rare Pokemon will swarm one route, if you go where she says, you'll find the Pokemon.
lucas/dawn little sister at some point will tell you she saw lavitar on news at route 206
you haft to talk to Dawn's sister and find Sentret first and evolve it ,but you have to national Dex first
Sorry, You cant get him on Platinum, The only way is with a Action Replay.. but you can find him in certain caves on Pokemon diamond and pearl but not on platinum u can get him on certain days, go talk to dawn or lucas's little sister newtest3
underground
No you can not battle dawn in platinum:( but you do work with her several times against team galatic