If I were to re-order that....actually, that's amazing. There literally isn't a single thing in that entire list that I wouldn't re-order. Like...Chou Gohan>>>Gohan Buu??? How is that even possible???
For starters, Vegetto never went Super Saiya-jin 2. This is confirmed by the fact that he a) only displayed a lightning charged aura in the initial power up, and appeared as a mastered Super Saiya-jin for the rest of the fight, and b) doesn't match Toriyama's theoretical sketches of a SSJ2 Vegetto.
Gogeta doesn't exist, really.
Chibi Buu is rather weak. He's, logically, the same type of base form as Aku Buu (Evil Buu/Skinny Buu), gave Goku less trouble than Fat Buu initially, and is even called "the Skinny Buu" at one point.
It is stated that at full power, SSJ3 Goku could "obliterate" Chibi Buu. I.e. Quite a bit stronger.
Chou Gohan displays a power that Goku states he didn't even know was possible...and in addition, makes child's play out of a form of Buu that Goku was terrified of fighting.
Gohan Buu is the strongest form of Buu. Probably the only individual in the series stronger than him is MSSJ Vegetto.
Gotenks Buu states clearly, upon first forming that he is the mightiest majin ever, past, present and future. All though "future" is proven wrong in a direct statement in which Gohan Buu testifies to being stronger than before, Majin Buu knows his own past...in addition, this form was clearly much stronger than Gohan. He nearly killed him, wasn't hurt at all in his fight, and even after Gohan is healed states that he is only back to his "former ineptitude".
I doubt Piccolo Buu is stronger than SSJ3 Gotenks. An increase from Piccolo would probably be so insignificant for Shin Buu, that you could barely tell the difference, and in their base forms, Chibi Trunks and Goten are stated to be weaker than him. Gotenks wasn't stronger than Shinn Buu by a huge margin, or even a large one, but it was enough to gain the upper hand and keep it. He managed to keep Shin Buu on the defensive the whole way through, although not without difficulty.
Shin Buu is positioned correctly underneath SSJ3 Gotenks, but literally everything else would have to be shifted around for him to land in the right spot.
Fat Buu is stronger than Aku Buu. I believe I've mentioned before in this topic. The Buu that remained after Aku Buu (the Skinny Buu) was expelled was not Fat Buu. It was his Good counterpart, what remained after expelling the wrath within him. It is even stated that their powers were divided. Likewise, the Buu that fought Chibi Buu was not Fat Buu. Fat Buu ceases to exist, atleast in his original sense, upon expelling that evil.
Skinny Buu (Aku Buu) should be lower than Fat Buu, as I've explained. You can place the Good Buu under him, as it's sort of a separate form. It's certainly a weaker one.
You've exluded a lot of others who should have placed on that list too...i.e. SSJ Gotenks (pre and post RoSaT), and Buff Buu.
MSSJ Vegetto>>>Gohan Buu>>>Vegetto>>>Gotenks Buu>>>Chou Gohan>>>Buff Buu>>>SSJ3 Gotenks>>>Piccolo Buu>>>Shin Buu>>>SSJ Gotenks (Post RoSaT)>>>SSJ Gotenks (Pre RoSaT)>/=SSJ3 Goku>>>Fat Buu>>>Chibi Buu>/=Aku Buu>>>Good Buu
Basically.
