Here is some toddler pants that I made from a pattern that was sized as 1-2-3-4. This pattern will be able to be used for several years. I made the size 2, I didn't want to cut the pattern so I would be able to use it for the next couple years.
The way that I was able to do this and not to destroy the integrity of the pattern where I couldn't use it later for the other sizes 3 & 4. I used a tool known as a tracing wheel and carbon paper. I traced out the size 2 and then cut the pants out and sewed them up. You can see in the picture above how the carbon paper traced out onto the fabric when using the tracing wheel tool.
These flower pattern pants shown with a yellow ruffle top that I posted about late last year, I think it was around September 2012.