Here's the first set of numbers I've posted in a while. In light of the recent guidebook-inspired epiphanies regarding Gotenks, I've tweaked my Majin Boo-arc levels.
Multipliers:
Super Saiyan ~
50x base
Super Saiyan 2 ~
100x base (2x SSj)
Super Saiyan 3 ~
200x base (2x SSj2)- Preferred because it works much better than the bloated 400x boost "suggested" by the SEG. We'll just say that only the physical "strength" gets boosted 4x, but not Ki along with it, and leave it at that, okey-dokey?

Super Saiyan 4 ~
500x base (SSj [50] x Ozaru [10])- Not relevant at all to this list, but I wanted to include it. It's part of the reason why I prefer 200x for SSj3, at the very least.
For the foreseeable future, I'm gonna stop bothering with "multipliers" for Fusion. It's too much of a pain and there's too many variables to consider, and I don't care as much as I used to. So Fusion characters will simply be where the story decrees they are, not where a formula does. Good thing that's how it was written in the first place. Any future reinstated formulas will be very loose and suspect to heavy "rounding."
Son Gohan - 19,500,000
(
Cell Games - 22,000,000)
Super Saiyan - 975,000,000
Super Saiyan 2 - 1,950,000,000
Ultimate - 15,000,000,000
- Gohan's lost a good amount of power from slacking off for the last 7 years, and is now trailing pretty far behind Goku and Vegeta, who have both spent that time training their behinds to the bone. He gets an unnatural and undeserved amount of power in his 'Ultimate' form.
Vegeta - 24,500,000
Super Saiyan - 1,225,000,000
Super Saiyan 2 - 2,450,000,000
Majin SSj2 - 2,666,000,000
Son Goku - 26,650,000
Super Saiyan - 1,335,000,000
Super Saiyan 2 - 2,665,000,000
Super Saiyan 3 - 5,350,000,000
- There's a sizable gap between Gohan and the other two, and a smaller but still significant gap between Goku and Vegeta, which the latter needs Bobbidi's magic boost to fill. Finally, Super Saiyan 3 is extremely badass.
Piccolo - 750,000,000
- Piccolo is also extremely badass.
Son Goten - 7,000,000
Super Saiyan - 350,000,000
Post-RoSaT - 8,250,000
Super Saiyan - 415,000,000
Kid Trunks - 7,500,000
Super Saiyan - 375,000,000
Post-RoSaT - 8,750,000
Super Saiyan - 435,000,000
- The kids are already strong enough to be a serious threat to Android 18 and even impress their elders when sparring and powering up. They get a way-too-generous-and-makes-no-sense boost from training in the Room of Spirit and Time for barely a week.
Android 18 - 275,000,000
Kibito - 25,000,000
- Strong enough that Gohan probably couldn't beat him without Super Saiyan. Though his physical strength must be severely lacking in comparison to his Ki level, since he couldn't lift the Z-sword like Gohan could.
Kaioshin - 750,000,001
Fused with Kibito - 2,000,000,000
- He's stronger than Piccolo for the sole reason of making sure I don't get bitched at. After merging with Kibito, he's still weaker than the Super Saiyan 2s, and useless against just about every form of Majin Boo.
PuiPui - 850,000
Yakon - 22,000,000
- PuiPui still sucks, and Yakon still sucks a little less.
Dabra - 1,000,000,000
- "About as strong as [an unspecified form of] Cell." He has a more-or-less even fight with Super Saiyan Gohan, but is assumed to be the better of the two. Goku and Vegeta could totally kick his ass.
Gotenks - 45,000,000
Super Saiyan - 2,250,000,000
Post-RoSaT - 55,000,000
Super Saiyan - 2,750,000,000
Super Saiyan 3 - 11,000,000,000
- Going with the guidebooks' implications for Gotenks here. He's "stronger than Gohan" his first time around. After his week in the Room of Spirit and Time, he's "surpassed Vegeta and the others." All in all, he's roughly twice as strong as the adult Saiyans' average. Huzzah.
Fat Boo - 3,500,000,000
- He's a bit too much for any of the Super Saiyan 2 folks to handle (as well as, by coincidence, Super Gotenks), but Super Saiyan 3 Goku could roll him up and smoke him.
Evil Boo - 2,000,000,000
- This "evil incarnate" form of Fat Boo got most of the power in the split.
Mister Boo - 1,500,000,000
- What's left. Got smoked by his evil side and Kid Boo later.
Super Boo - 11,000,000,000
- Boo's evil side is now in control, and he's able to access much more of his South Kaioshin-fueled power. More or less even with SSj3 Gotenks.
Gotenks-Boo - 22,000,000,000
- Super Boo + Gotenks. Easy.
Gohan-Boo - 26,000,000,000
- Super Boo + Gohan. Also easy.
Buff Boo - 15,000,000,000
- Super Boo's power from South Kaioshin temporarily flares up in full while he's undergoing his "reversion" to his natural Kid Boo self.
Kid Boo - 5,250,000,000
- Fought on more-or-less even grounds with Goku, who could have wiped him out if he'd managed to gather enough power.
Vegetto - 700,000,000
Super Saiyan - 35,000,000,000
True Power -
∞
- Self-explanatory. I mean, it's Vegetto for cryin' out loud.
Well, there you have it. Read 'em and weep. No, seriously, I'd better see some freakin' tears.