What are the best skill fruits for Elphidran Aqua?

[KurokaiSO]

I'm currently preparing an army to fight Blazamut Ryu with an army of Elphidran Aquas. Yes, I'm aware that there are much better Pals like Jormuntide, but this is the way I prefer, as Elphidran Aqua is one of my favorite Pals!

I have bred them with the strongest passive skills.

(Demon God, Legend, Lord of the Sea and Musclehead)

What skill fruits would you recommend for the best outcome compared to my current one being Acid Rain, Tri-Lightning and Hydro Laser? And could I switch out Musclehead with Serenity perhaps? Any recommendation is appreciated, thank you in advance!

[Yal]

Serenity gets better the longer cooldowns there are on that pal's moveset IMO. Numerically 30% less cooldown means 25% higher DPS and then the flat +10% attack boost brings up effective power boost to 35% but because of how defense works it's not so simple in practice.