Pairing anglers and dwarf lionfish is a very delicate operation, they can both potentially eat each other. The wartskin angler can't eat an appropriately sized lion, but a lion could eat a small warty. The marble mouthed angler which is showing up more frequently could be sized appropriately. The other popular anglers like the sargassum and painted will grow large enough to eat the lion. Unless very good at sizing and understanding the angler can eat a fish up to it's own size, and will try even larger, this many times ends badly.
Most people don't keep the snowflake alive long enough to reach it's full potential, a well cared for snowflake will reach close to 30" and about a 1.5" diameter, my personal recommendation is at least a 75g, at least a 4' tank.
Like others have said, the powder blue will require at least a 6' tank for activity and aggression.