RPG Game that Switches to Fighting Game on random battle.
Cross of Venus comes to mind: https://www.youtube.com/watch?v=2x16b2Fg-BM Not NES, obviously.
It doesn't lock you to facing the opponent from what I remember (in case that affects what you consider a fighting game).
Neo Geo Pocket Color has similar sprite limitations to NES (64 8x8 sprites), and had rather a lot of fighters. But it had no sprite per scanline limit from what I can tell. Here's some gameplay footage from SNK vs. Capcom: The Match of the Millennium: https://youtu.be/jHHr8lBQsL8?t=1m4s
A lot of Neo Geo Pocket (Color)'s library was fighters.
But managing lots of animation in this way Is more suitable for CHR ROM bank switching on NES and NES Maker's Mapper is CHR RAM. I've been working on a CHR ROM NES graphics data tool and I'm importing character graphics from Match of the Millenium to test it.
I had written a long thing about how to potentially do it in CHR RAM, but I guess it boils down to:
I wrote a test ROM that did 32 pixel per frame scrolling (horizontally). That means it could push 128 bytes to the PPU every frame. A tile is 16 bytes. Therefore you can update about 8 tiles in a single frame. (It may be possible to do slightly more than this... but eh...)
Since you probably want the characters to move and animate independently, this is 4 tiles per character per frame. If the frame you want to display needs 12 tiles and none of them are in memory, you need to wait 3 frames for it to come out.
You can make faster attacks by ensuring they're always in memory. For instance: Say your 12 tile attack can use 4 tiles of the head from idle. Now it can come out in 2 frames. If all the tiles it needs are always in memory, it can come out immediately.
So the strategy would be to have hitstun frames always in memory. (Since the opponent can always interrupt your attack by hitting you.) Any projectiles the player can use also need to always be in memory. And then you want as many tiles as you can fit from the first frames of the fastest attacks always in memory. With all those things in, you can use whatever is left as a scratchpad to put tiles for new frames. Imagine a three frame animation. 12 tiles per frame. If you want each to play for 1/60th of a second, you need the first two frames always in memory.
Before frame 1 is displayed, 4 tiles from frame 3 are put in the scratchpad.
Before frame 2 is displayed, 4 more tiles from frame 3 are put in the scratchpad.
Before frame 3 is displayed,the final four tiles are put in the scratchpad. Literally just in time for it to be displayed.
But the more tiles an animation uses, the slower it has to be. (Or else, it'll just have to use a lot of the "always in memory" portions, but eventually you run out of that space.)
The Indivisible boss is like 30 tiles per frame. It'd take 8 frames to write the tiles to display a new frame that wasn't in memory assuming two of them. With CHR ROM bank switching, this doesn't matter even a little bit. One can display any frame from any character at any time no matter how large. (There are some caveats, but they wouldn't matter much for a fighting game.) That's what I mean when I say CHR ROM bank switching is better for this.
(What do you know, turns out I wrote a lot again. Better explained this time around, though.)
@R Cohrs: I'm not sure if you're suggesting NES Maker should be able to do it because those games do. Understand that not all NES cartridges are created equally. Little Ninja Bros, TMNT Tournament Fighters, and Radia Senki - Reimei Hen all use MMC3 with CHR ROM bank switching. The cartridge NES Maker targets doesn't have the same options those games had. Just as those games didn't have the option to play over 20 minutes of streaming audio: https://www.youtube.com/watch?v=3w8atFA2fk0 Extensions in NES cartridge hardware greatly changed what was allowed, even back in the day. It's also not as easy to just target a new cartridge type.
Of games I know, Battletoads gets the closest using a similar setup. It still had to really be designed around. How many tiles your characters take up affects how fast your animations can be played and where they need to be. With MMC3, none of that matters.
Edit: And just because I guess the inevitable followup question is "Why not just target MMC3 as well?" The answer is that they're different in many subtle ways besides just CHR RAM vs CHR ROM.