First, let’s define what I mean by “most powerful”. Bulma quite obviously is not physically as strong as any of the Z fighters and she most definitely is not skilled enough in martial arts to pose any threat to a serious fighter (Satan could take her out if we’re being honest). So how can she be the most powerful character you ask? Well, by “powerful”, I mean wields and controls power.
Bulma doesn’t fly, she doesn’t shoot laser beams from her body, and she isn’t a master martial artist, but she has something no other character in DB has. Bulma has the unwavering, undying, and 100% loyalty of Goku, Vegeta, Trunks, and Bulla.
Bulma has been around since the beginning of Goku’s journey on earth. She has been one of the defining characters that helped mold and develop Goku into the person he is today. Due to their journeys and adventures Goku developed that sense of family he has with her. Goku doesn’t view family in the traditional sense. Anyone that he cares for gains 100% of his loyalty and friendship. They become his “family”. Therefore Goku would die before letting anything happen to Bulma as she’s part of his family just the same as Gohan and Chichi. Goku is also… on the childlike side when it comes to mentality. Bulma knows this and has always used it to be able to garner a bit of control over Goku (well as much control as anyone can have in regards to Goku). So this gives her arguably the most powerful fighter in the world on her side.
Then we move on to Vegeta. This should need very little explanation honestly. Vegeta laid the smack down on Beerus himself because he hit Bulma. Vegeta powered up out of sheer anger and wanting to protect his love to a level that exceeded even Goku’s power levels until he went SSB. So we know without a doubt that Vegeta will also die before allowing harm to come to his wife.
That’s 2 of the most powerful beings in the entire universe now ready to lay down and die for her. Now we have Trunks. Trunks is in the same boat. Powerful being, loyalty and love for Bulma. Lay down life for her, etc. Now we have a trio of warriors that, barring interference from actual gods, realistically is not going to be beat by anything short of total galactic destruction.
So we’ve covered her initial stable of protection. We know that she has bodyguards capable of cosmic destruction with the ease of delivering a pizza. This is just scratching the surface of how powerful and, dare I say it, devious and cunning Bulma really is. Now let’s delve into the differences between Chichi and Bluma.
Chichi is constantly chiding and badgering Goku to “get a real job” and trying to push Gohan into a life of academia instead of taking the warrior’s path. Bulma, on the other hand, encourages her saiyans to train and become more powerful warriors. She has no problem with them going down the warrior path. This is because she knows her position of power relies on Vegeta and Trunks being powerful warriors. She is raising warriors. She is essentially stockpiling the equivalent of nuclear weapons.
Now this might all be dismissed as overthinking, grasping, and trying to delve far too deep into her psyche and character, but I have another issue that supports my idea. Pilaf and gang. Mai being the most important part of this equation. As I stated earlier, Bulma has been around since just about Day 1. She’s been with Goku on just about every adventure he’s had in some shape or form.
This means she’s met Pilaf and gang. This means she KNOWS who Pilaf is. This means that when Pilaf and gang show up, she recognizes them but refuses to tip her hand and plays dumb about who they really are. She allows them to stick around because she knows she can keep an eye on them to keep them out of mischief, but then also because she sees a suitable mate for Trunks in Mai after the black arc.
She has already betrothed Trunks and I can easily see her pushing Goten and Bulla to become married in the future, further cementing her position of power. Bulma knows exactly what she’s doing.
She has very quietly amassed any army of loyal saiyans ready to die for her at the drop of a hat. She has never died in the series. She has never been allowed to be harmed beyond a smacks over the years. She knows that she is the safest person in the universe because of this and has slowly been amassing that power base for decades now.