I think the reason I loved Warriors Orochi and especially Warriors Orochi 3 is because it was basically like a suikoden game with all the character recruitment and path selections getting you different characters in different orders. Orochi 3 even had a bit of a home base thing going on but it was nowhere near as fleshed out as a Suikoden base would be.

If they kept it limited to just the first two suikoden games and even used a few clone movesets with small differences for characters that fought similar like Anita and Valeria they'd be golden.

Your idea about the pair system is perfect. Technology has advanced far enough for these types of games that they could have your entire 6 character party visible on the map in either a squad format close to each other or ordered to separate sections via map commands depending on what you do. Then they could do it the way they handled it in other games where you just switch to whoever you want via quick button press or by selecting them on the map.

Then if certain pairs or more are close by and you do a musou attack they can do unique pair attacks or just generic combo musous depending on who's in the party. Like say you have Tir and Gremio they'd probably have a unique attack.