I dont remember where I got them all, honestly, but I remember the last two: One came from that RR Dog in the bocing ring, and the last came from the indian guy all the way south.
The ones you get from quests aren't the same as the actual ones you'll find during the weekends ^^ Just use your scouter to scan for NPC's that give quests instead of randomly walking around.
The quest ones are related to a questchain ending at lv20 where you wish for a package, no other options.
You'll get lv20 shenron rares, 10k zeni item, dragonball scouterchip.
With that chip in your scouter you'll be able to 'see' mobs on the minimap that might drop dragonballs during the weekends.
"Dragonballweekend" is from fridays 1100 till sundays midnight korean time, so 2½ days each week.
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