Board 8 > Shiny Drowzee get... to evolve or not...

(+) Yeah! (+)

I've been trying to make a Living Dex (not easy since I've never attempted it in all my years playing Pokemon) as well as trying to complete the National Dex in Y (it seemed like I was/was going to get close enough while doing the Living Dex to be worth attempting). Right now I'm focusing on filling in the gaps from Gen I through II and I noticed an odd little one that I didn't have on anything that I could transfer to Y was Hypno. So I went to Soul Silver and tried to catch one west of Vermillion and within two encounters I found a fucking shiny Drowzee. My luck finding shinies over the years has been dreadful. All the ones I have I was either explicitly shiny hunting for and thus doing stuff to increase my odds, distribution events (I missed the Eternatus, when I finally got a chance to get to GameStop the codes were gone.. damn..), found in Pokemon Go where the shiny odds are absurdly high to begin with (at least I found an Eevee the other day that I can make into a shiny Umbreon!!!) or the Red Gyarados. To just bumblefuck upon one in a mainline game has never happened to me before (well it did once but I wasn't able to catch it). So this one I was super excited to catch and now the only question is.. do I leave it as a Drowzee or evolve it into Hypno?

Definitely evolve into shiny Hypno