CosmicTanooki364 said:
In 2D Mario:
~Drop the live system and add Rayman Origins level of challenge and difficulty.
~Give Mario a basic melee attack that he can do as Small Mario/Super Mario.
~Allow Mario to progressively learn new abilities and moves as he progresses throughout his journey.
~Stop relying so heavily of the standard world motifs.
~When multiple characters are playable, Give Mario a ability that makes him stand out from the rest instead of making him the "Jack of all trades" character.
In 3D Mario:
~Drop the live system.
~Bring back the Super Mario 64/Super Mario Sunshine style health system, but compensate by making the enemies tougher.
~Allow Mario to progressively learn new abilities and moves as he progresses throughout his journey.
~Bring back large hubworlds with things to do and NPCs to interact with, maybe add some side quests?
~When multiple characters are playable, Give Mario a ability that makes him stand out from the rest instead of making him the "Jack of all trades" character.
Dropping the live system will make both 2D and 3D Marios to be just as tedious and atrocious when you get a game over. It'll be even worse if it involves going back to the title screen like in Castlevania Symphony of the Night and the other Metroidvanias in the Castlevania franchise (includes Lament of Innocence and Curse of Darkness). Seriously that was the AVGN's complaint towards games that take him back to the title screen. But if there is a health upgrade option like in the Metroidvanias then it's okay.
I got something to add on.
Limit Peach's kidnappings to only 2 and make her a playable character.