Who is the biggest idiot ?

[Monkey D Goku]

I think Vegeta is more of a in the moment strategist than a plan it out ahead of time kind. Especially when he stole the dragonballs from Frieza that was pretty good.

[soulnova]

Kaioshin has gotta be up there. For having all the resources of a god, he knew absolutely nothing and was repeatedly dumbfounded by the saiyans. How could he have possibly missed the fact that at least three mortals had surpassed his own strength?

Oh yes. Specially the part when they were headed to find Babidi and they were telling Piccoro, "Uh, you should be careful because they might get the darkness of your heart, Durrr" with Vegeta standing 2 meters from them, you know, the Saiyan who purged entire planets.

I'm surprised that in the last thousands of years Kaioshin didn't hear the legend of the Super Saiyan. I mean... I believe even King Kai had some knowledge on him... KING KAI.

Also, just because I consider Vegeta an idiot & not a good strategist doesn't mean that I don't like Vegeta. He is one of my favorite characters. I'm just objective.

I hear you. I still love our irresponsible Saiyans.

[Piccolo Daimao]

Out of those three main Saiyans, Vegeta, obviously. His ridiculous narcissism outweighs his genuine battle intellect. Why? He goads Freeza into transforming and merely laughs it off to Gohan and Kuririn by saying that he won’t change that much (did you forget about your mistake with Zarbon, or—I dunno—your own transformation? Oozaru?), and he runs into a battle with a newly-transformed Freeza without even testing his power (big whoop, you can see when his blast—that wasn’t even aimed at you—is coming), because he thinks he must’ve become a Super Saiyan by now after getting it wrong twice (with both Gokuu and himself).

He allows his ki to be absorbed by #19 and has to bluff his way out of a fight with #20, he deduces that (after becoming a Super Saiyan) he must be stronger than Gokuu on account of being the prince of an extinct race, he allows Cell to absorb #18 and reach his complete form just so he can have a good fight, and he orchestrates Majin Boo’s resurrection just so he can fight Gokuu (and when he realizes how much shit they’re in, he knocks out Gokuu to fight Boo alone).

More often that, his gaffes actually end up helping the villain because he’s so blinkered by his royal dick that he doesn’t realize that he’s constantly making incredibly risky gamble after gamble without ever learning from them. And when he’s pushed into a corner, rather than thinking up a strategy, he just starts firing barrages of ki blasts, to the point that when Boo does it, Gokuu says that he “copied Vegeta’s move” (despite Vegeta not actually using it in that fight).

I'm surprised that in the last thousands of years Kaioshin didn't hear the legend of the Super Saiyan.

He did. Did you forget Kibito telling Gohan to turn into a Super Saiyan to see if they can really help them?

But I think I'll put Kaioushin's...let's say, inexperience and lack of hindsight...down to him being the youngest and weakest of the Kaioushin, who may've died before they could give him the entirety of his training for the job.