Why TMNT2, if I may ask? Don't get me wrong, I'm looking for it myself, but I recall you not being too big on beat 'em ups in general.
True, I'm not. But I already had Gekikame, and I had bought TMNT partly for nostalgia's sake (it's one of the few NES games I had as a kid) so I figured I'd complete the trilogy. It's technically the better game anyway, with each turtle having more personalized attacks, special moves, etc.
Also, we seem to be both after Chip 1 at the moment.
Zen Intergalactic Ninja is something I've been considering.
The Immortal was never **officially** released on the Famicom. I have a Famicom copy sitting in my collection, and it was made by a Chinese / Taiwanese company circa mid to late 1990s
Illegal pirate carts don't really count. That's like saying Recca was released in the US around the 2010's because people started making repros of it. Doesn't quite fly.