I doubt it would take a year to slightly tweak the mechanics for a small area, ignoring any potential balance as is. People, please stop assuming the TC wants a giant change or anything like that. It's very clear he's talking about a small mode where you play with differences, no different from Invisible Melee, Giant Melee, etc. It's pretty much identical to Brawl's Special Mode, where you can adjust all that stuff. To the point that you could literally just add all these things to 4's Special Mode and call it a day.
It's not as hard as anyone is making it here. And no, it would not be the most overused mode, since it wouldn't be balanced around like regular Smash. All the Special modes were unbalanced by design and the game wasn't centered around it, making only normal Smash worth playing in Tourneys.
Also, stop suggesting to go play Melee, it's a pointless statement that misses the point of why this is a fun idea; You can't play any of those new characters in Melee or with its overall mechanics. It's not a worthwhile suggestion due to that alone. Remember, SSB's biggest draw is the characters, and the mechanics only help. Some want both in combination, and that was not ultimately doable outside of hacking/codes, which is kind of silly. But that's what people want sometimes(and there's nothing wrong with that anyway).