OK I figured out the problem - part of the auto-correction tool I added was replacing "pokemon" with "Pokemon" so it made the URL for the image wrong. I have fixed it so that it only works for regular text.
However, I would prefer it if you used our sprites from PokemonDb. Some sites block "hotlinking" images (like Bulbapedia). And IIRC Pokemon Stadium moved all their sprites to different locations, breaking all the old links. And sometimes sites go down, like Pokecheck did a few weeks back.
Ours are pretty easy to find, just go to the sprites page, click the desired sprite, copy the code in the third box labelled "Markdown" and paste it directly into the box. The sprite will then come up.