Crouch cancelling ruins uptilt forward tilt and down+b approaches.
I disagree about tornado, since if they CC it you can just use the rest of the duration of the tornado to move away from them. This assumes you approach with an earlier part of the tornado, but who just like tornados (yeah that's a word) to approach from the opposite side of the stage anyway lol. If you do that, you've got a lot more to be worrying about then CCing.
Ftilt is true at low percents, but you can use it off a retreating WD safely.
As for uptilt, the biggest problem with approaching with it is that it has like no horizontal range compared to something like ftilt, dsmash, or even jab, so anything will beat it out. Like KK said, comboing mostly, occasionally it can be used as an AA, but a lot of things will beat it out. Usmash is better for that, it's disjointed as ****.