I had a thought about how to give heavyweight characters more options without actually changing how their basic movesets behave...
What if non-smash A button moves for HWs had variable frame data, based upon how long the button was held?
For example, DK's ftilt has the hitbox active from frame 9 to frame 11, with the FAF after being 38. If the player held the A button instead of tapping it, I envision it extending the duration of the move (including stretching out the hitbox).
So for holding the A button, the hitbox would now extend from 9-16, with the FAF being 43 (or it could be much more noticeable, like 9-21, and FAF on 48). It could hypothetically even be variable, where the # of frames the A button is held = the number of frames the move is extended (with a cap, of course), but that might be too complex overall.
It would be great to also extend this to aerials, though not necessary (not sure about smashes, in which you'd have to press and hold A after you've started the attack or something).
The idea here would be that, since HWs generally have bad frame data, they could choose when to extend a move to provide more coverage when they need it, without giving them any faster attacks, per se.
I suggest only doing this for HWs because they should be the best "boxers" in the game, as controlling space around them in key to success. Yet small, fast characters make this difficult because of how easily they can bait a move out of a HW and then punish it.
By giving the HW player the ability to vary the duration of their attack, the HW player would also be forcing the fast player to guess how long the hitbox will be out. If they see DK's ftilt start to come out, they can no longer just assume that his hand and active hitbox will only be out for 5 frames, nor that DK will be able to shield on frame 38 after it.
I'm guessing it would be far too late for a change like this to happen, but it would be a better solution to making HWs more viable outside of super armor and throw followup kill confirms. :\