This patch makes it so you can use the original Bowser fight but have it cut to a sublevel after the fireworks finish. Useful if you want to use the Bowser fight but also have it cut to custom credits or cutscenes. It can be configured in the asm file to teleport the player to whatever sublevel you want. It is also configured to teleport the player depending on if it is Mario or Luigi (Player 1 or Player 2) to separate levels. Useful if you want to have separate cutscenes depending on the player that defeated Bowser.
I'm rejecting this for optimization issues. The main one is that the entire code to teleport the player is basically duplicated for the Mario and Luigi cases, besides the instruction to set the value for $00. An optimal way to do this would be to load the value depending on the current player, then join the two branches to execute everything else.
There's also some minor optimization issues: the first is the "CMP #$00" after "LDA $0DB3|!base": LDA already sets the Z flag, so to check against 0 the CMP is redundant. Also, the hijacked code could be optimized in different ways to avoid executing the four NOPs: for example, you can do "autoclean JSL BowserFightWarp : RTS", or use "autoclean JML BowserFightWarp" instead and, in the code in free space, jump back to the RTS with "JML $03C7A6" instead of using RTL.