I can't believe I missed the bulk of the heavy debate. Well I think I can still contribute.
If we look at other fighting games and compare common strengths and weaknesses, we notice that
Strengths:
Beastly normals
A GTFO move
Armor on some setup attacks
Better range on normals
Lenient health
High damage output
Some good pokes
Satisfying to win with
Crowd favorite
"Simpler to use"
Weaknesses:
They are combo food
Mediocre to bad frame data
Huge hurtboxes
THEY ARE COMBO FOOD
A hard time to approach outside of jump in approaches
Usually no projectile (except sentinel really)
COMBO FOOD!
They really don't have combos of their own and rely on one or two sparse hits to hopefully setup something
COMBO FOOD ¯\_(ツ)_/¯
Must rely on defensive tactics yet the frame data doesn't allow them to do so
Their shields are by in large harder to use to actually protect yourself as you usually find yourself shielding for your NEUTRAL position
Rushdowns eat the up
COMBO FOOD (ಥ_ಥ)
Easy chip damage
Have to play linearly and must have a punish on fleek to even have any success
IMO to win with a heavy, ur opponent must mess up first which isn't a strong or great thing to rely on
COMBO FOOD. ͡° ͜ʖ ͡°
Simpler to use as ur game plan was made linear so u play predictable.
The problem with SMASH is the heavies in this game have all the weaknesses listed but seem to lack the strengths. DK has great normals, DECENT NOT HIGH DMG output, a lack of GTFO move, higher mobility, lenient health in terms of weight (a double edge sword); blah blah blah. The reason I use DK is because he is or was considered the best giant in the game for a while. The truth is though, Bowser is the ONLY giant to have the strengths and weaknesses I listed and he STILL WAS LISTED AS GARBAGE FOR A BIT. For Bowser to get good they had to increase his mobility (from previous iterations) and then give him a grab confirm. Apparently giving a character like that a grab confirm is all that's needed for the character to get better, but it doesn't help with theain AMD core problem they have. The problem they have is they get zoned, they get rushed down, a meh CQC, and get combos that deal tons of damage. A grab confirm won't alleviate that at all. I see people say things to the extent that characters are supposed to have weaknesses..... But that's because they design characters to fail IMO. Snake, KD3, and Sentinel are the biggest giants to be considered to be high tier that really messed with the meta. Snake and Sentinel are dedicated Zoners that betrayed the prototypical midrange brawler giants were. They still had weaknesses like other giants, but they strived upon having a better design. If ur held back by the developer's design instead of ur personal skill or the character's SPECIFIC weaknesses, then that is kinda silly.
TL;DR
Design will never allow giants to succeed and giant mains should be OK with that even if it is silly. (Even big body main KBR took EVO 2015 with just big bodies in UMvC3).