RPG, many characters join, but you just use the first few the whole time

Rance 6 and Quest (7) have a mechanic where characters return home after a certain number of battles in an area, so you have to rotate them. Sengoku Rance works similarly in dungeons. 9 also has SRPG-style battles where you deploy many units each time and sometimes need to distribute them into multiple groups. A game where it is kind of true is Like a Dragon: Infinite Wealth. The last two characters to join need to catch up in power, mostly exist after you have a full party of other characters available, and seemingly aren't that great anyway.