Right now we have to upload the sprites from the website to imgur, and then from imgur to the forums (Let me know if there's a shorter way). This is a very very very long process especially when uploading many sprites at once, like in forum shops or team pages.
Please allow uploading images from some famous Pokemon Sprites websites such as :
pokemondb.net/sprites/magby
or
pldh.net/dex/sprites/magby
Thanks.