We'd need to play the game to determine that.
I never said it won't and can't be played competitively. I'm only in doubt it can be to the extent people want it to be. Like Mario Kart. There's a lot of people here because they're fans of the game and want to play it. But I can tell the competitive people are going to probably like the competitive side of Smash.
As a member of the Competitive Smash community, I can say this:
The divide between casual and competitive Smash exists for obvious reasons, and the same will happen with practically all competitive games ever made, ever. It's just a bit more extreme in Smash Bros. Also no, this game has the potential to go far beyond the likes of Mario Kart, it just needs the support behind it which we pretty much have garnered up in this site.
Anyway back on topic with what
@Venus of the Desert Bloom started, I think the best strategy actually might depend on the map. For example, Walleye Warehouse. It's a small, straightforward map with two side paths. In Splat Zones, the Zone is in the middle. From the gameplay I've seen, it gets hectic around that area, with 1 on 1 duels happening constantly. But there's always a few people who sidewind around the map, come in for the kill, and quickly return back from where they came to avoid getting themselves splatted, as of course dying puts your team at an obvious disadvantage for about 5 seconds (would be longer for a bigger map), which could be the difference between a gained/lost zone. (IDC if this is a run-on sentence) After a couple players are down, you need to quickly fill the zone with your ink within the given 5 seconds. As such, you'll need the mobility to get around all while having the potential to kill quick and retreat, and you need to be able to fill the zone quickly. I believe the best set of weapons for this map is:
Brush, Splattershot Jr., .52 Gal, Blaster.
However, It has been revealed that Blackbelly Skatepark's Splat Zone version has two Zones, and is a more open map with a central sniping point. I think getting the first kill and then guarding the sniping point is key for this map, so I believe that because of the open-ness of the map and the distraction between guarding two zones, the best choice of weapons is:
Splat Charger, Splattershot Jr, Roller (x2)
By surrounding the central point in ink, you create a safe zone in which the sniper has guaranteed protection from anyone with a medium-close ranged weapon. Since you have to keep up the ink and spread it quickly to provide this, you'd need two Rollers to keep up the ink and your enemies away.