Trying to create some registrations layered with Accordion Sounds Idea ?

That would depend on the genre of music doing played, no? ... acoustic jazz - clarinet; Cajun - violin; Mexican - trumpets; etc., etc. ...
Listen and your ears will tell you ...

Pairing different types of Accordion sounds work well together,

Almost every Mexican Norteña band uses accordion and alto sax. Very common sound you’ ll hear throughout Mexico and the South West USA. I think the Mexican band “ Los Tigres del Norte” started this particular sound back in 60’s and it’s been going strong ever since then. If you’re in any heavily populated Hispanic community in these parts you will hear this sound everywhere, weather you like it or not!

I Brazilian choro music you hear a lot clarinet and accordion playing lines together.

Check this out!

https://www.youtube.com/watch?v=Zes9yQaSwQk

Paul, that's very interesting ...
Our band in NY started in the late 50's at a time when the tenor sax was the popular sax ... Our sax player preferred the alto - he was a big Paul Desmond fan ... we told him he had to play tenor and he played both for a while until it became all alto, no tenor ... it actually helped make 'our sound' what it was ...

I know you play accordion too Tony. Did you ever play it in your band?

Yes, Paul, for several years ... I then transitioned to Cordovox
https://images.app.goo.gl/QvmHB6eWzDSVFrvJA
and in the early 70's an uncle who played classical piano gave me a Fender Rhodes that he had and did not like the action ... I would lie the Cordovox on top of the Rhodes to use its many sounds, and then eventually just played the Rhodes with the band ...

Interesting Tony. I suppose and your alto player played some lines together then.

What kind of music were you playing in your band with the accordion?

Paul,we primarily played for weddings and dinner dances, so we played the popular music of the day, as well as Great American Standards, polkas, Cha Cha, etc.

Sounds fun Tony. I’m sure the accordion and alto worked will together especially on those polkas!

It did, Paul, but it was much more than that ...Mine was very similar to this one, and for most songs I used a low tone like the second one demonstrated in the video which gave a full, rich sound ...
https://www.libertybellows.com/shop/c/p/...0-x32994377.htm

My current accordion (I purchased 57 years ago). It is a custom made (Bachalachio ??) and had Sano modify it to stereo amplification. And purchased the Sano stereo amp..

Back to my Original Post,

Firstly I think it depends on the Actual Accordion sound begin used, it is being played as a solo instrument or an ensemble. But as a Solo Instrument the Accordion seems to work well with strings such as Violin, Pad Sounds, and Vocal Sounds such as choirs, another sound that works well is a piano sound.

These are my findings so far.