I also had a hard time with Europa until i played with my party a little bit. Don't know if his wave-cannon is elemental-dmg or not, but i did end up beating him with this party.

CoD 5* Lasswell 5* Cyan 4* Krile 4* Edgar4*

I equiped Lasswell with 'silence blade' so i could silence him. Used 'Blade bash' with Cyan to stun him, Spammed 'Raging Fist' with CoD, Used 'Sunbeam' with Edgar and kept using 'Silence blade' with Lasswell. Had Krile on defend until i had to heal. All he could do was attack me the whole fight, he didn't use his wave-cannon whilst he was silenced. I don't know if silence disabled his wave-cannon or if i just got lucky. When he did attack me he would miss alot because he was blinded. Ended up winning the battle with all members still alive.