I apologise if there's already a guide for this.
1. save some pokemon on to your computer.
to do this, go to a pokemon sprite website ( like pokemonelite2000 for example, then right-click the pics you want, then click "save Image as.." and on the red box below, mke it all files or BMP

2. select the pokemon you want and open them on MSpaint. I selected doduo and magnemite for the tutorial.

3. put the sprites together on one file. I recommend you save it as something else at this point

4. next split the pokemon up with the tools in red, if you need to make the file bigger that's fine. I would save again here.

5. delete the part's that you don't want and put together everything else.

you can even recolour as an extra option.

You have now made your sprite
6. Save,then select you're pokemon(using the tools on step 4) and put it on the upper left corner.Then click Edit -> Attributes and type in on both boxes 80. the white bit (I'll call it paper) should get smaller.
if your sprite is too big, doesn't matter just click undo and make the size to your fitting (you can also do that byclicking on a tiny blue square on the bottom-right of the paperand move it).
Now save and exit MSpaint
7. open up your sprite in a program like photoshop or something ( I use a program called PhotoFiltre)
click "save as" and make sure that the line under the name is PNG (as on the picture below.)

It is now ready to upload to the Internet.
that concludes my tutorial

Questions or comments?
just PM me or reply here