Bojack is probably pretty close to Perfect Cell (*pre* self destruct). At the time, Piccolo is stronger than a base Super Saiyan but below a Full Power Super Saiyan (which is in turn, not enough to beat Bojack).
So in short, he's strong enough to be of some use in a fight, but pretty outmatched.
End of series... no real way to tell how much stronger he's gotten.
^ Pretty much covers it all. In DBZ forums it's commonly accepted that Piccolo gets stronger as time goes on but it's pure speculation. But since he really has nothing to do but train I think he can handle Bojack at the end of Z.
Bojack stomps Piccolo. Piccalo never won a fight in the whole series. All the years of training and fusing with Nail and Kai and still he could not win fights.
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The reason Piccolo didn't win many fights is because he was the guy right after the Saiyans, who were always the big saviors who ended all the big fights. He was incredibly powerful, but number 2 doesn't look so glamorous when your number 1's are so high end.
Piccolo was the guy who put up a good fight against pretty much every arc bad guy to some extent, and made them work during the fight. Then the Saiyans took over.
He was also the guy who most easily took out the liutenants or sub-bad guys. Like during Lord Slug when he killed his entire Elite Guard in under three minutes.
Your right I had to watch those again but your right he did wipe out Coolers Armored Squad. What I meant to say was he never really took out any significant players in the series. And Im remiss if he was even able to take out any androids. I think not though.
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