I think it's BP related; it seems that the game records your team/lineup when you reach your highest BP, and then that team will be used for survival trial checkpoint.
Take my groupmate for example: atm he only has 30k-ish BP with a team composed of Water Main-Guy-GNW Choji-Jigokudo Pai. However, when I run into him in Survival Trial, the team I encountered is Water Main-Haku-Suigetsu-Guy, with BP around 32k. This is the team he used for our group summon fight, meaning he only used it twice per week, 10 mins each time (I think), and the guy tend to switch back immediately after the event is over; yet whenever I run into him (Survival loops alot of teams), this is the lineup that was used.
If out Survival trial lineup is based on our regular lineup before each reset, then I should have run into the 1st team compo, no? But instead I always run into the 2nd one, the one with higher BP. Thus I think it BP-based. This post was last edited by Watanuki13 at 2017-4-25 22:02