he's ok, but he's outclassed by its peers in terms of being useful; zard's a killing machine where as venus's is a freaking brick wall, blast falls short of either but does make up for its lack of use by being able to spin and haze, but hazing has gone out of fashion, so, blastoise with it
also note: starmie/gyarados/vaporeon are all native to the kanto region (vapor SORTA is...) and they were... ARE, infact, tonnes more useful than blast, and if you want to argue blast can stand its ground better than those 3, then we can mention slowbro/lapras who WAY outclasses blast's staying power, and if you wanted defense then kingler/cloyster take the cake back in R/B/Y
fire alternatives: all are weak to ground, only zard can fly (moltress is a better version of zard, but you can't breed moltres and zard's moveset's more versatile)
grass alternatives: the first decent one comes after the 6th gym (exeggcute/exeggutor) and that only became fact after 3rd gen