>>23403757In the gamesDiantha knows Sycamore, calling him "Dear Augustin", it is safe to assume they are pretty close (another flirt of the prof? Childhood friends?). In the anime they interacted once but didn't seem that close or maybe just pretended not to be. Note that he called Diantha's assistant "Minami-chan" which can make you think he knows her well.
Lysandre probably worked in the lab of the prof. He tells you the prof "taught him a lot". They are probably close friends. ("He needs to be protected" n-no homo).
Lysandre and Diantha interacted a lot in th games confronting their view on beauty.
To finish Malva is an Elite 4 and a member of Team Flare. She knows both Diantha and Lysandre.
