There are no specific requirements so far, besides the deck playing somewhat decently and mostly free of bugs. For now, I am in charge of the decks that make it into the standard lists. Just work on the deck as much as you see fit, I'll test it a couple of times, maybe ask you to fix some issues I find. Then, if you give me your permission, I'll add the deck, while properly crediting you for your work, of course.
It doesn't matter, how strong or meta-relevant the deck is, or how well it performs (to some degree, it should work on a very basic level at least). Many of the implemented AI decks are not particularly strong, they are not meant to be. Just like your Watts, they are made for nostalgia, or to highlight an old archetype/character.
If you are referring to the Six Samurai AI from this
post, that was way before we even implemented features for players to add their deck to the existing AI. It does not work with the current version of YGOPro anymore, and the author doesn't seem to be around anymore. If it would still work, and I had permission from the author, I would have added it a long time ago.
Edited by user
| Reason: Not specified