hey what is this!?
auto enemy chars? i must have to try they!.
well is very insteresting. i think in that possibility, since i do something similar for the outfoxies, that change the mode to p2 moves p2 character or cpu moves the p2 character in else game mode.
anyway, take a look to the double dragon 2 save marian code. i found new codes that i must join together for posting in a week or two.
these are codes that allow you to play as else enemy (not auto) or boss. however the code dont works correctly (you see the char billy sprites and the enemy sprites in the same place) so i be forced to find another hard code, that finally avoid the blinking, and this makes you can play as else enemy. yes!
however, as you can imagine, this cause lots of little non important glitches, as that if you push 2 times forward, the headbutt not exist for that enemies as abadede, so you make a animation from when abadede break the wall in stage 1.
also i do the same codes for dd1 and dd2. and also for dd3, but those are different and requires 4 codes at same time joined and a lot of work in searching new enemies in there.
the good new are that yesterday i almost ended the search and test in dd3, so i almost can start the traslation of the codes for posting in 1 or 2 weeks when i have some free time

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the bad news are that in dd3 the enemies dont works right with the jump. so maybe you are forced to use the billy jump with they because you cant jump right with enemies, so you cant kill bike enemies for example

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however the 4 secret characters that you can buy during the game, works perfect.
so only enemies cant jump right due to that incompatiblity problems, beetwhen player and enemy chars. is sad, but of course is also a normal thing. because is very very rare can play as one enemy

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so only give me some time more, and you all can see this bizarre thing i do...
EDIT: this is a old post, so i hope you come here someday and read this...

well, i already tested your "auto select char code". is fantastic! please, can you tell me how you do it?
i suppose that maybe you use "equal" when you grab a enemy and "different" when not, or something related for find it...
well, in dd1 intro when the images (in there are images and no real enemies) go for puch marian, if you use my select enemy code that i will post, you can see that one of the chars (marian i think) dissapears, and the enemy show the animation of the two togheter.
so maybe it something like that, who makes that the animation changes in the wrong character, and for some raison making the player changes to one enemy.
however it have some fails, since sometimes you cant attack others and viceversa

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thats no happen with my select char code, however the game suffer a little slowdown, due that load billy and also the enemy because the codes i make. but it works and is not an important thing after all.
about can select mission: this is not possible, due that game play all stages followed. but you can find a code for start in final mission since it load as starts the stage 1.