AI_Object3B

Rom offset starts at $17DA8

To switch the code into another slot, change the 2-byte rom offset at
$16AC1. $17F86 ($BF76) to $1800F ($BFFF) are available to create the 
code freely. The bottom of the rom which is $1FF10 are also unused space.

If created from scratch, please don’t forget to change the JMP’s and LDA 
ram locations or it will not properly. Also to BNE or BEQ the code where is 
properly pointed if expanded from the original point. 

$BD98> A5 31:   LDA CurrentStage
$BD9A> C9 07:   CMP #$07                     ; Wily 2 level               

If you choose to add another stage, use BEQ where the boss number is 
located (to A0 00) then add CMP (C9 XX) for another current stage.

$BD9C> D0 13:   BNE ++                        ; $BDB1 ($17DC1) 
$BD9E> A0 00:   LDY #$00                      ; Cutman
$BDA0> A5 1B:   LDA ScrollPosScreen
$BDA2> C9 1C:   CMP #$1c                      ; Screen Number for Wily 2.
$BDA4> F0 02:   BEQ +                         ; $BDA8 ($17DB8)

If you’re adding more screens with boss numbers, 
repeat the LDY, LDA, and CMP codes above. BEQ the code to 84 AC after each entry.

$BDA6> A0 04:   LDY #$04                      ; Elecman
+
$BDA8> 84 AC:   STY FightingBossNum
$BDAA> A9 02:   LDA #$02        
$BDAC> 85 3E:   STA BossCurrentStrategy         
$BDAE> 4C BCBD: JMP $BDBC (This is where the 01 special object comes in.)
++
$BDB1> C9 06:   CMP #$06                      ; Works for Wily stages?
$BDB3> F0 0E:   BEQ $BDC3               
$BDB5> A6 1B:   LDX ScrollPosScreen         
$BDB7> BC CABD: LDY $BDCA,X     
$BDBA> D0 EC:   BNE $BDA8               
$BDBC> A9 01:   LDA #$01        
$BDBE> 85 68:   STA ForcedInputFlag         
$BDC0> 4C B1BE: JMP RemoveObject              ; $BEB1
$BDC3> A9 42:   LDA #$42        
$BDC5> 9D 2004: STA ObjectFlags,X     

$BDC8> A0 CC:   LDY #$cc
$BDCA> 20 33F5: JSR InitObjectDefaultSpeed       
$BDCD> A9 13:   LDA #$13        
$BDCF> 9D E006: STA ObjectType,X              ; Footholder
$BDD2> 20 63F6: JSR CreateEnemy               ; $F663
$BDD5> B0 0F:   BCS $BDE6
$BDD7> A9 02:   LDA #$02        
$BDD9> 9D 2004: STA ObjectFlags,X     
$BDDC> A0 CC:   LDY #$cc        
$BDDE> 20 33F5: JSR InitObjectDefaultSpeed       
$BDE1> A9 4C:   LDA #$4c        
$BDE3> 9D 8004: STA ObjectPosX,X     
$BDE6> 60:      RTS Return

Wily 4 boss tables. I really do not understand how is coded without anything pointing to these bytes or a loading/comparing tables. 
I haven’t found the breakpoint of the code but it’s unknown to me!

These bytes are utterly pointless if the code is created from scratch.
Edit these boss numbers to fight them in Wily 4 only starting at screen 1D.

Rom offset $17DF7

$BDE7> 02:      .Bombman
$BDE8> 03:      .Fireman 
$BDE9> 01:      .Iceman
$BDF0> 05:      .Gutsman

A5 31     LDA CurrentStage
C9 09     CMP #$09                      ; Wily 4, uses actives for $3B enemies at checkpoints after dying.
D0 03     BNE +
4C 7E 90  JMP StageBegin                ; Resets all actives and palettes targeting the chosen level.
+
4C 81 90  JMP StageBeginFromDeath       ; Every other level resumes as normal.