Have these been uploaded to Danbooru yet?

http://www.pokesho.com/4koma.html

It seems funny from what I can see in the pictures.

soara 4koma, though they're not pooled for some reason.

Some of them, at least. Search for soara 4koma. If you ever want to see if an image is already up here, one way is to go to Upload, paste in the image URL or file source on your computer, then click "Find similar".

EDIT: Gah, beat out.

You could save them, then get the md5 checksums of them using an application.

Then search for: md5:<md5 checksum>

If nothing is found, then no.
If something is found, then yes.

Though these could have different checksums than ones already posted, so just search for something like: pokemon 4koma

I just have a firefox quicksearch "iqdb" -> "http://iqdb.org/?url=%s".