Renzoku sucks, blatantly. It eats away your ki bar, and you get a few blasts, which suck terribly.
As for scattershot, just take distance, and do a tele attack. If your playing some noob who can't aim, you push scattershot on and keep moving with turbo, doh, they won't hit you. Just tele-attack, easy as that.
Anyway, renzoku sucks, horribly.