ParanoidDrone
Smash Master
I've only recently started online matches so I've only seen one spammer, a Kirby who was absolutely in love with his Stone move. He did get a few kills on me, once when I screwed up returning after an edgeguard and another when I got careless, but overall I was able to beat him soundly without any real effort. But no matter how often I punished him for it, he never did anything more complex than simply not using Stone sometimes.
I guess what I'm saying is that at least some spammers do so because it's literally the only tactic they know, and to be fair it probably works against similarly-(un)skilled players and low level CPUs. But I feel confident saying that any tactic which revolves around the repeated use of a single move can probably be worked around with any character, albeit with varying degrees of difficulty depending on the matchup.
I guess what I'm saying is that at least some spammers do so because it's literally the only tactic they know, and to be fair it probably works against similarly-(un)skilled players and low level CPUs. But I feel confident saying that any tactic which revolves around the repeated use of a single move can probably be worked around with any character, albeit with varying degrees of difficulty depending on the matchup.