Competitve Player Answer: The Splat Dualies are definitely good for getting through enemy ink and getting crabs, however suction bomb as the sub limits your poking ability by a lot, meaning you shouldn't really push unless you're doing it with another teammate.
Actual Answer: Just play whatever you have fun with, man. If playing vanilla dualies is how you have fun while playing splatoon, just play them. Don't worry about if they're "good" or not (good being a relative term and an impossibly vague word.) Unless you're on a comp team, you shouldn't worry about the viability of the weapon you're using, and if you are on a comp team, see above answer.