There's an artist who sketches the winner of the contests in each contest hall. When you win the Master rank, he will do a more detailed one. He will ask you if he should take it to the museum, so tell him yes. He'll take it there. (It doesn't take him very long since that contest hall and the museum are in the same town). If you go to the upper level of the museum, you can view the picture.
You have to win the master rank contest at lillycove city
While in Lilycove City, you can find Captain Stern in that museum place where Team Magma/Aqua are standing by. I forgot how to get rid of them, but once you do, you can find Captain Stern in that museum place I mentioned.
You deliver Devon's Goods to Captain Stern who is in Slateport City's museum.
If you win a Master Rank contest, a picture of your winning Pokemon will appear there. Cool contest - red frame, beauty contest - blue frame, and so on.
If you manage to get to Master rank Pokemon Contest, there will be a lot of people in the crowd, among them is an artist. When it's you're turn to show your Pokemon to the crowd, make sure there a heart pops up over his head, because that means if you win, your Pokemon will be drawn in full color, and will be placed in Lilycove Museum, making you a "super sketch model."
If your Pokemon scores five hearts or more in a contest, you'll get a portrait of it that will go to the Lilycove Museum.
The art muesum is located at Lilycove City, at the top left.
You must win a Master Rank Contest by a certain number of points above the others, then the artist will paint your Pokemon and put it in the Lilycove Museum.
It's in Lilycove City.
You have to win the master rank contest at lillycove city
OK so first you will need to win the Master Rank of the Pokemon Contest to one Pokemon then talk to the painter and it will be in the museum.
Win inthe Master Class Contest then talk to the guy in lilycove museum :-)
in the oceanic museum
Oceanic Museum in Slateport City
When you win first place in a Master Rank Pokemon contest, and do exceptionally well, there is a chance that the artist outside of the contest hall will show you a portrait of your winning Pokemon that he was inspired to make because of their (cute-/smart-/etc.)-ness, and will ask you if you want it displayed in the Art Museum. If you agree, then the portrait will be displayed.
While in Lilycove City, you can find Captain Stern in that museum place where Team Magma/Aqua are standing by. I forgot how to get rid of them, but once you do, you can find Captain Stern in that museum place I mentioned.
In the Lilycove City, if 5 paintings of your Pokemon who won the contest are exhibited to the Art Gallery's second floor, the Curator will give you a Statue of a Legendary Pokemon... But about the Art Dealer outside, I still don't know what to do with him...