I am always surprised by the distance that DownB ends up covering.
http://www.youtube.com/watch?v=T_yKhIcrSEU
@3:19
If you pause about 3:20 where Mr.Concon has started the downB, look at the distance that he covers in the span of the time it took DEHF to do a simple short hop laser.
Its this general situation I end up finding myself in where I think I am at a relatively safe distance, but they end up randomly starting a DownB and charging at me and getting underneath me before the laser comes out. Or it ends up trading rather poorly. It doesn't help I am not sure how to DI the DownB. At lower percents, holding for merely ASDI works, but other times I end up slamming into the ground due to ASDI at higher percents.
As I said, trading laser with DownB doesn't seem to help (at least I always seem to DI poorly and end up on the ground or in the air due to the last hit). Depending upon their direction control, air dodge doesn't work since it last so long. The really only thing against it is Nair/Dair to try beating it out, but I never got around to looking into it more. YoshQ never does it much, while a couple of random luigi's I have played do. Its one of the few things in the luigi match-up I feel shouldn't be happening, but does.