[Trexmaster]

Innates are what stick.

For testing, I used Evoker/Hexer, went into fight, fled, then joined a battle in progress after switching to Grand Summoner/Engineer.





Those were from the same fight and on the same character, mind you.

And I also had the 8 item slots from engineer, while still having all the non-innate skills from Evoker/Hexer (active skills).

EDIT: Passives also seem to function from the classes you swap to prior to joining, as I could install the youkai in question. If I recall, though, active skills from the classes you have when joining wont apply. I'll probably test for that again need be.