Just recently I tried getting back to doing my Wii Fit on a regular basis. My basic controller was acting strange even with brand new batteries. I purchased the better controller and a remote nunchuk. Today I tried several times to do the parade march. The controllers both seemed to work fine when there was a slight gap between hitting the circles. As soon as the gaps narrowed as the targets scrolled down my controllers couldn't keep up. To give you an idea of the difference. A few months ago I one or two misses, five or six "ok's" and all the rest "perfects". Now the misses are forty or fifty. Much yelling and swearing has taken the place of exercising. Any ideas?
In system settings (from the main menu, click the wrench in the lower left-hand corner), there should be options relating to the Wii Remote's sensitivity. Messing with those might help fix the issue.