Masquerain in depth
The antennae bluff
The source animal isn't a moth, even if the design makes it look like one. The reference is the Fulgora laternaria, the lanternfly, a tropical hemipteran whose swollen head and hindwings carry eyespots —circular markings that imitate vertebrate eyes— meant to scare off birds. The choice fits its pre-evolution: Surskit is practically copied from a water strider, another hemipteran, so the whole line stays within the same insect order despite the jump from pond to air.
The rest of the design works with the same motif. The antennae aren't functional antennae but a signboard, and the Pokédex entries insist that their expression changes: angry by default, drooping and sad when humidity rises. It's the only species in the Pokédex whose weather warning is painted on its body.
Ame, moth, masquerade
The Japanese name is アメモース, Amemoth, combining 雨 —ame, rain— with the English word moth. English changes one half and keeps the other: masquerade, the masquerade, plus rain. French, Maskadra, keeps only the mask. All three languages point to the same thing from different angles, a disguise and an overcast sky, and in all three the name describes its behaviour better than its body.
Surskit's after-effects
When it evolves, it loses the Water type but not the habits. At level 1 it retains Whirlwind, Water Gun and Soak, three moves that no longer get it any bonus, and through TM it can still access Surf, Hydro Pump, Waterfall and Liquidation. None of them help: without the type behind it, Hydro Pump hits less hard than Hurricane, which also comes with STAB. The case is a good illustration of how inheritance works in an evolutionary line's movepools, where moves accumulate even when a type disappears.
It also inherits Sweet Scent and Stun Spore —the latter at level 26—, two support tools that barely appear elsewhere among Flying types and that make more sense in a Double Battle than any of its orphaned Water attacks.
Forty points for free
Generation VII did it the biggest favour in its history. Its base total went from 414 to 454: Special Attack rose from 80 to 100 and Speed from 60 to 80, two tweaks that changed its category from nuisance to usable Pokémon. The Speed increase is the important one, because many opponents in its range cluster just below 80.
Even so, it's still a long way from serious Quiver Dance users. Volcarona has 135 Special Attack and 100 Speed to start with, and learns the move with a body capable of surviving the turn it takes to set it up. Compared with Hoenn's other two winged bugs, Dustox and its twin, Masquerain at least has an ability that changes something. Its type shared with its pre-evolution, Bug, is the only thread that survives the evolution; the other evaporates with the water on its wings.