We remember a Pink Panther Cartoon where he's chased by an evil cloud,
give him a bad time raining on him. Do you know the name of the
cartoon or do you even know on what (vhs/dvd) collection we can find
it?

gugelhopf..

The episode you are referring to is entitled "Sprinkle Me Pink". 
Originally released in November of 1978. Unfortunately, I have been
unable to find a collection that has that particular episode.  You can
find a listing of the released Pink Panther cartoons at "The Pink
Panther Source Guide" at
http://www.high-tech.com/panther/source/pinklist.html. You can see a
complete list of the Pink Panther Episodes at
http://www.pazsaz.com/ppanther.html

You may be able to find someone who has the episode you are looking
for by posting a request in the alt.video.tape-trading newsgroup at
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&group=alt.video.tape-trading

Thanks for your question.  If you need any additional clarification,
please let me know.

Regards,

-THV

Search Strategy:
pink panther episode guide

References:
The Big Cartoon Database
http://www.bcdb.com/cartoons/Other_Studios/D/DePatie-Freleng_Enterprises/The_All-New_Pink_Panther_Show/The_Pink_Panther/index.html