this would be a neat thing to do for Mario 3, not a "redux" nor an "antigrinding" hack, but something in a similar vein
change all mushrooms to "fire-leaf mushrooms" so go from small to fire-leaf Mario (as seen in Mario Adventure hack, fly/shoot fireballs/swing tail all with one power-up, maybe just make them stackable, idk
replace fire flowers with hammer suits and leafs with Tanooki suits for all the levels, i know you'll feel o.p. but isnt that the point of these kinda hacks.
i would replace the lives system with a deaths counter, negating game overs and lives, make 1-ups give you 50 coins, and add a coin counter that just counts the total # of coins in a playthrough,
put a question block box at the beginning of each water stage containing a frog suit,
implement the "item slot" hack (press select to switch to a stored item, more like SWM), do away with item storage and card flipping and toad houses and roulette all together (maybe replace them with something better.
add 3 star coins (or 5 "yoshi" coins per level) and a counter/way to see them
make lvels re-enterable, and worlds re-visitable (like SMA4 after you beat it)
streamline the gameplay and make it easier, but in a fun way. i find myself spamming savestates to keep my tanooki suit and hammer suit too the point of makeing the game a chore sometimes, lol