challenge combo's practical? GET OUT OF HERE!
seriously challenge mode is designed to help you break that mode of you not being able to combo things worth shit, a mode in which it helps the player understand how the characters special moves or combo's work, not for you to whine about.
all the challenges are made to challenge you, so sure they are hard, sure you can't use them in a real fight in some cases...but keep in mind they are there to get your creative juices pumping and for you to actually have execution skills.
I just typed the same thing...a lot.
5$ get.