need to find a photo i saw on tumblr

You'll need to search again, using the exact same terms you used in order to find the image in the first place. A descriptive search like this is extremely difficult.

I was afraid of that. Ive tried searching google/google images and still no success and i cant quite remember how i came across the photo in the first place just knew it was on tumblr

In google image search you can limit your results to only tumblr by adding inurl:tumblr to your search. But I couldn't see any likely candidates searching for
pikachu inurl:tumblr

Have you thought about looking at your browser history? If you know roughly when you found it. Or just search for tumblr in your history. Depends how far back your history goes and how long ago you found it.

unfortunately i found it a while ago and ive cleared my history by now.
Ill try the inurl thing and see if it works

*snicker*
Somebody's been watching porn.

lol