Slowking are regular Slowpoke who suffered a peculiar event. The King’s Rock they rarely hold attracts Shellder, and gets bitten on its head instead of its tail. The poison that some Shellder secretes reached Slowpoke’s brain, turning it extremely intelligent.
This craft appeared in a Japanese magazine, and therefore there is only a lined version. There aren’t too many lines though, and I think some people will like to have this in their craft collection. it only has 6 pieces and one page, so you should have built it in no-time.
By Jupiter, info from Bulbapedia.