^AKB vs SKE... none really come up.
There's the mini-challenges that show up every few episodes, they do in the studio with a classroom backdrop. With them getting a short time to learn to do some trick, like juggling or playing a yoyo. Most studio episodes have a mix of members from the groups. Enjoyment level is pretty unstable.
And there are the big "sport festivals" they've done (swimming, ball games, rope-jumping, etc...). Which sometimes include some SKE girls, but not head-to-head AKB vs SKE.
The festivals mostly have DVDs out already:
http://www.akb48-dvdcatalog.com/catalog/index.html#tvFor recommendations.
This one has AKB only if I remember correctly. A Shukan AKB episode that must be watched would be the Dokkiri SP.
http://www.akb48-dvdcatalog.com/shukan_sp7/Actually. Basically any DVD with a SP label is probably a good watch. With a load of members showing up, and a lot of easily understandable physical challenges.
Then there's the earlier legendary episodes where they go out and just do crazy challenges.
Like the first episode in '09 where Shinoda, Acchan and Kojiharu stand in the middle of a Harajuku street. And seeing if anyone can recognize them. Do that now and they'd be bombarded.
And the Gekikara Club. Which had a lot of laughs. It had girls like Rena, Yukirin and Miichan eating spicy food. Reaction queen trio right there.
The early episodes are a great watch just to see current popular members doing such crazy stuff in the past.
Like having girls like Yuko, Moeno, Tomochin, Miichan and Kojiharu holding paper cups filled with boiling water, riding a crappy van. With the windows open just to have the Winter wind blow at them. Doing that now would create lawsuits aplenty.
The show has been around for 4 years now, you're not gonna finish it in a week. So take your time.