Alright I have a few things for you there yuuichi.
1. Don't use default Paint colors.
2. You should try to tackle sprites before heading into pixel art as your outline is too thick.
3. NEVER! Save as jpeg or bmp. Save it as PNG it is the extension that is commonly used and excepted for any sprites or pixel work.
Read some tutorials that are on the site and you will get better. You have potential, just keep working at it and you will do fine.
Vişne Tanrıça said draw a ball and i did a pokeball to be specific
i have two sprites but i havent fininshed the trainer one
really they arent that good, if you want help with spriting i can do some descent ones, look at my pixel art,
Think about he is made of pure flamesprite doesnt look as though the light is coming fro anywhere
7/10