Seeing that you've made four posts all about game instruction manuals, I thought it best to try and answer all your manual questions in one post.

For WarioWare: Mega Microgame$ instruction manuals, you can find a few of them on Ebay and Amazon.

http://www.ebay.com/itm/Wario-Ware-Inc-Mega-Microgames-GBA-Manual-Booklet-ONLY-/220657597978?pt=LH_DefaultDomain_0&hash=item336037be1a

http://www.amazon.com/Instruction-Booklet-Advance-Manual-Nintendo/dp/B006F9QPOK/ref=sr_1_fkmr1_2?ie=UTF8&qid=1333132235&sr=8-2-fkmr1

As for WarioWare: Snapped!, because it is a DSIware game, there is no printed instruction manual for it. Instead, all the basics are included with the game itself. If you would still like one though, there is a fan-made instruction manual that explains the basic settings of the game.

http://www.gamefaqs.com/ds/959022-warioware-snapped/faqs/56186

However, for Game & Watch Gallery 4, Rhythm Tengoku (GBA), and Osu! Tatakae! Ouendan, there doesn't appear to be anyone selling these manuals at the moment. Even though it may take a while, it would always be a good idea to consistently check the listings on sites such as Ebay, Craigslist, Amazon, etc, for people selling the manuals you're looking for.