How many powers did Fat Buu show?

[withheldforprivacy]

They're at least three (his initial power, plus his two statedd power ups).
Do you think he powered up again after that?

 

[Let's Go Fearless!]

Chapter: 460 (DBZ 266), P10.6
Context: before the smoke forms into Boo
Gohan: “…N-no…A stupendous ki…A stupendous ki has swelled up…Th-this…”

Chapter: 462 (DBZ 268), P1.2-4, P2.5
Context: after Boo beats Dabra
Gohan: “It-it rose…Majin Boo’s ki rose explosively…He’s str-strong…Too strong…This is unbelievable…”
Trunks: “…What the…!? This time I feel an incredible ki over there too…What’s going on?...”
[ ]
Goku (talking to Vegeta): “…It changed into an outrageous ki…So Majin Boo really isn’t anyone ordinary after all…This ain’t no time to be doing this kinda thing…! We’re the ones who let this monster out…”

Chapter: 464 (DBZ 270), P11.6
Context: after Vegeta insults Boo and he lets steam out of his head
Kuririn: “Hey…That monstrous bastard’s ki got even huger.”

Chapter: 466 (DBZ 272), P1.3
Context: after Boo’s big attack makes a crater
Vegeta: “…Wh-what the?...Ridiculous; he’s st-strong, and to top it off immortal too…Damn it all…”

3 Power ups IMO.

 

[GSM123]

Pretty much what Fearless said.

 

[Super Neko Majin Z]

Didn't he show a higher level against SSJ3 Goku or was I interpreting that wrong?

 

[withheldforprivacy]

The explosion against Vegeta wasn't a power up; it was a wide area attack, like Piccolo against Goku at Budokai.
Against SSJ3 Goku, no power up was implied.

 

[Let's Go Fearless!]

The explosion against Vegeta wasn't a power up; it was a wide area attack, like Piccolo against Goku at Budokai.
Against SSJ3 Goku, no power up was implied.

Chapter: 466 (DBZ 272), P1.3
Context: after Boo’s big attack makes a crater
Vegeta: “…Wh-what the?...Ridiculous; he’s st-strong, and to top it off immortal too…Damn it all…”

 

[withheldforprivacy]

The explosion against Vegeta wasn't a power up; it was a wide area attack, like Piccolo against Goku at Budokai.
Against SSJ3 Goku, no power up was implied.

Chapter: 466 (DBZ 272), P1.3
Context: after Boo’s big attack makes a crater
Vegeta: “…Wh-what the?...Ridiculous; he’s st-strong, and to top it off immortal too…Damn it all…”

Vegeta just comments on the combination of Buu's power with his regenerative capabilities. No power
up is mentioned.

 

[Let's Go Fearless!]

That depends especially once Buu creates that giant crater, he started destroying Vegeta yet he couldn't do the same thing before that.

 

[GSM123]

That depends especially once Buu creates that giant crater, he started destroying Vegeta yet he couldn't do the same thing before that.

He actually wasn't trying, he just bothered to get serious when Vegeta used the finger attack, but since the 2nd power up he should be able to one shot him.

 

[Let's Go Fearless!]

Indeed, it's also the reason why I view that power up as raising his effort than powering up.

 

[Super Saiyan Overlord1007]

1. Initially when Vegeta saw him as no threat, Dabura thought he wasn't a threat, Gohan believing he could beat him if he went all out.

2. After being insulted by Dabura, he powered up and thrashed him, Gohan, and Kaioshin without much effort and Vegeta sees that he spoke too soon and Goku believed that if they teamed up than they could handle him.

3. After being insulted by Vegeta another Power-Up where he's beyond the reach of SSJ2s (Non-fused SSJ2s that is)

One probably would assume he powered before Vegeta turned himself into a garden statue but I dunno.