How do I get a treecko,how do I trade with someone to get a scaptile,why..

You can choose treeko as one of your 3 starting Pokemon and it will evolve in to Grovyle and Sceptile at somewere between lv 30 and 30 (i can't remember exactly.

You don't need to trade treeko with anyone to get a sceptile because you just level it up to evolve it. If you already started the game and you didnt start with treeko you need to find someone with a treeko and trade it from their game

You don't need to trade the starter Pokemon to evolve them

First of all just level up the treeko to lv.36 to get a sceptile.

Second, if the treeko is a female, breed it with a male salamence that knows crunch. The baby treeko will at least have pound,leer, and crunch. Now evolve it into a sceptile. If you saved the tm for dragon claw, teach it to your sceptile. Also, make sure he knows leaf blade. Finally if you saved up 48 battle points go teach him thunder punch. It should now know leaf blade, dragon claw, crunch and thunder punch. Also what ever you do, DON'T listen to people that tell you to teach a Pokemon 4 moves of the same type. What would you do if you ran into something you couldn't kill? I only suggested the moveset because it's pretty much the best one a sceptile can have. Hope you use this answer and (I forgot to mention this earlier),dragon claw can be found at meteor falls. You need surf and waterfall. If you need help with making teams or teaching Pokemon moves, I will do my best.(sometimes I have other names but you'll know by my answers).