I know you've reiterated that a team of four is enough, but perhaps you should add in Cloyster/Walrien and frosslass as pokemon 5 and 6. atleast this would give you options of using different hail team formations when doing double battling, instead of always being stuck using the same four pokemon that might not always work.
Example: you could go with the frosslass+explosion team sometimes instead of all the time, if you felt their wasn't too much fo a threat from protectors/ghosts.
Just give it a thought, it seems unnescesary to limit yourself to 4 pokemon when you don't have to.
Ahaha. Yeah I know. That's why I said "I may add Froslass and Walrein/Cloyster as possible alternates." That's what I meant.
I only came up with the initial four in order to create a core. Trying to come up with a team of six is, at least for me, overwhelming when starting from scratch.
And on a side note, StarmanXL has always made note of the cliche Froslass/Abomasnow lead; the original four was my attempt to break away from the norm. Of course, the reason why the Froslass/Abomasnow lead is so cliche is because it's good, a tried and true pair. It is of great consideration!