4th Gen How do I stop Pokemon from evolving in Platinum?

[enderkool]

I'm currently doing a challenge in Platinum and one of it's rules is that I can't evolve my starter. I have no idea how to stop a pokemon from evolving without the everstone. Can someone please help? Thanks in advanced.

 

[Palamon]

Press the b button, and the Pokemon will stop evolving. I do recommend you get an Everstone, though, because you'll have to press the b button every time your Pokemon tries to evolve without one.