As for 手筒花火
http://images.google.co.jp/images?um=1&hl=ja&tbs=isch:1&q=%E6%89%8B%E7%AD%92%E8%8A%B1%E7%81%AB&sa=N&st art=0&ndsp=20
(Maybe you are talking about this.), you can't give it a shot.
It is not because you are a foreigner. It is because you are a temporary traveler. You should take training in advance.
As for Strength test, Lifting something heavy is popular.Stone,Straw rice bag, Rice cake.You might give it a shot.
Sumo is also traditional strength test at festival in Shinto shrine.