Well, I found an actual boxed original copy of Pocket Monsters on Genesis, and what immediately stuck out was NTs "Carson/KaSheng' name at the top right
If it's on this one, then it's probably safe to assume the whole ES series of games(which besides this one include Hercules, Mario Bros. 2 and Sonic Jam 6) were published by them. It also would seem to disprove that ES has any link to ESC, Waixing's old alias, since if Waixing made it I don't see any reason they wouldn't publish it themselves since they do that with all their Famicom releases.
I take it Pocket Monsters 2 is from them also, though as far as I know there's no versions that exist with an ES ID number.
BTW, how do we know NT are just publishers and not developers? I musta missed that