I have been using Mari0 and SMBx programs for some time because I love the idea of simultaneous multiplayer. Great news is that CorpseGrinder and Ti have produced the first ever simultaneous SMB mod.
I intend on building off of their work as a template for bringing my mario mods to have simultaneous multiplayer. The hack has most of the original information in the same order but in different locations. This post is to document the addresses where information is located, and to explore options for bringing in some new features into the game that most smb hacks have (reverse red piranha plants, for example).
Feel free to contribute - I find it useful documenting my notes online for my own benefit to pick up the project later if I need to temporarily suspend it.
x8e77 - Change Mario's starting lives. 02 is default (3 lives). 7F is max (128 lives).
x8053 - Change Luigi's starting lives. (credit to Corpsegrinder)
x844D - Change Mario's color. In different order than normal.
x???? - Change Luigi's color. Luigi shares the palette with Green Enemies (normal) and Red Enemies (fiery)... so technically he will have different colors in every level type. Bowser's axe color will override any custom luigi's palette.. so far bowser's color is set to identical to luigi's palette.
xA471 - w1-l1 level data