Did Adult Gohan...

[Rocketman]

If he went SSJ2 against Kibeto, why did Vegeta say he was weaker then he was when he fought cell... I always thought that he just went max level SSJ.

Because Gohan had been sitting on his ass eating corn chips for seven years. His SSJ2 form dropped in strength from disuse.

[Conan the SSJ]

Just gotta love how so many different points of views clash when two different canons are concerned. Seriously guys, let's not try to think too much about it and determine who is absolutely right because regarding the anime, there is no right answer. Manga, okay, Gohan never went SSJ2 after the world tournament, fine! But in the anime confines, the lightning is NOT an essential aspect! This is proven in Vegeta's 1 minute struggle with Kid Buu, as well during some parts in the Cell Games where Gohan has the SSJ2 hair length but no blue lightning. If anything, in the anime, it just represents moments of intensity; blame Toei. That's just my outlook on it, just as I posted before:

Well, I just go with the idea that in SSJ2, lightning represents moments of intensity, not essentially a sign that someone has to be at SSJ2. You look at the Cell Games for instance, an example when Cell's ready to blow himself up and Goku's teleporting himself, there's no lightning around Gohan though his hair is still at the SSJ2 length, as well as when his arm is injured by Cell. There are other examples as well in the series (movie 12 for instance, while non-canon, Goku is clearly at SSJ2 judging by the appearance of his hair feature). I basically go with the idea that, in the anime, ... Keep in mind, this is just my point of view, so almost everything in my list is pretty debatable:

Gohan going SSJ2 -
1: After 16's head was destroyed, and still hurt by the Cell Jr.s torturing his Father and friends, Gohan fully goes SSJ2 for the first time in order to battle Perfect Cell (dropped out of SSJ2 for a bit after Kuririn came to comfort him following Goku's death).
2: After Cell's return in his Super Perfect state, I believe following this line of Cell's in the dub "So, which one of you cowards is the bravest!", Gohan immediately transforms back.
3: After Goku saved Gohan's life from Bojack's crushing grip, Gohan goes SSJ2, quickly killing Bido and Bujin and defeating Bojack.
4: At the 25th Tenkaichi Budokai, to show Kabito what he was really up against, Gohan transforms in a fantastic display revealing himself as "the gold fighter".
5: Against Dabura when fighting in his normal form wasn't doing any good, transforms to SSJ2 when crammed inside a mountain.
6: Against Babidi and Dabura when ready to take out Buu's ball before it went maximum power (and powering up to the level he was at in the Cell Games when flash-backing beating Cell), Gohan is transformed to SSJ2, essentially in the level in his first battle with Buu.
7: When removing the Z Sword, he transforms to attain it.
8: With no Ultimate/Mystic power-up, and Bebi-Goten nearly destroying himself, Gohan is forced to transform to SSJ2, immediately being taken over by Bebi afterwards.
9: Following being purified and healed by Kabitoshin, he briefly transforms in order to give SSJ4 Goku his energy, however reverts to normal after seeing Golden-Oozaru Bebi-Vegeta ready to kill them all.
10: As Uub's inner attack on Bebi-Vegeta begins, Gohan transforms right back as Goten and Trunks transform to SSJ, they're joined by Pan, in order to contribute their energy to SSJ4 Goku.
11: In battle against Super 17, when everyone's normal forms were having no effect, Gohan transforms swiftly as everyone else go to their respective maximums.
12: In order to give Goku his energy to defeat Yi Xing Long, Gohan takes off the scholar glasses and transforms, having a short encounter with Yi Xing Long, then giving all the power he could to Goku.
13: As the battle with Yi Xing Long draws to an end, Gohan returns with Trunks and Goten for one last battle against Yi Xing Long, transforming to his maximum.

Goku going SSJ2 -
1: While fighting Majin Vegeta, after being energy binded to a mountain and hearing Vegeta's monologue about how "Kakarrot"'s always humiliated him, Goku powers up noticeably and the rest of the battle is SSJ2 Vs. SSJ2.
2: When powering up ready to battle/stall fat Buu, Goku transforms right to SSJ2, soon enough reverting back to normal to demonstrate the levels.
3: During Goku's example transformations, demonstrating "the Super Saiyan beyond a Super Saiyan", he goes SSJ2 as he's gearing up to transform to SSJ3.
4: While power demonstrating for Goten and Trunks, Goku briefly transforms to level 2, showing the boys how to ultimately go SSJ3.
5: During Goku and Vegeta's short tag-team fight against Super Buu (w/t Ultimate Gohan, Goten-and-Trunks, and Piccolo) as Vegeta's pride got in the way to fuse, Goku goes SSJ2 in order to help Vegeta against Buu, eventually being knocked back to normal with the fierce prince.
6: At the start of Goku's battle against the mental thought-form of Ultimate Gohan, he transforms to SSJ2 to battle, however by the moment he and the thought-form begin the Kamehame-Ha battle, Goku is oddly reverted back to SSJ.
7: Inside Buu's innards against the mental Buu, seeing that a blast at SSJ couldn't even dent Buu's head, Goku and Vegeta together transform and handicap-battle until they're beaten bad enough back to SSJ.
8: When Kid Buu launches his planet-obliterating ball attack, Goku quickly transforms to SSJ2 with Vegeta in order to pick up Gohan, Piccolo, and the kids to teleport from Earth, reverting back to SSJ as everyone is transported to the Kaioshin world.
9: After winning Rock-Paper-Scissors against Vegeta, Goku transforms after thinking Kid Buu's fallen asleep, fighting the first portion of their battle at SSJ2.
10: Following saving Vegeta's life, Goku briefly transforms when beginning the second round against Kid Buu as he's powering up to SSJ3.
11: As SSJ wasn't quite strong enough, Goku briefly transforms to SSJ2 in order to push back the Spirit Bomb back to Kid Buu, reverting to SSJ after the final brief scene in Hell as he realizes Buu is beaten.
12: During the battle against Hildegarn, after Ultimate Gohan's been knocked down for the count by Hildegarn's second form, Goku noticeably goes SSJ2 in order to find a weakness, though is soon knocked down back to normal.
13: During battle against Hyper Metal Rilldo, Goku shortly transforms to SSJ2 in order to shield/block against a massive attack from Rilldo, but for some weird reason immediately reverts back to SSJ afterwards.
14: During Goku's second power up to SSJ3 against Bebi-Vegeta, there's a very brief moment where he's transformed to SSJ2, then transforming right on to SSJ3.
15: As Vegeta is proposing a battle of sport on a bridge, Goku goes SSJ2 for one more battle against his old rival, but a stomach ache for food reverts him back to normal as he and Vegeta laugh it off.
16: At the very beginning of his battle against Super 17, Goku's transformed to SSJ2 as he and 17 land their first hits, but in the next moment/episode, he's reverted back to SSJ for the rest of their first round.

Vegeta going SSJ2 -
1: As Babidi takes control of Vegeta's mind, amplifying his power, Vegeta soon enough transforms to SSJ2 as he's being converted to Majin status, staying SSJ2 until he's self-destructed against fat Buu.
2: When Enma tells Vegeta of Majin Buu's survival, Vegeta goes SSJ2 out of anger at his failure, destroying a bit of Enma's palace.
3: As Vegeta and Goku are at SSJ to start their battle against Super Buu, Vegeta goes SSJ2 following the dub line of "The Saiyan race will not fall again!!".
4: Up against SSJ3 Gotenks' and Piccolo's mental thought forms in Buu's innards, Vegeta angrily goes SSJ2 demanding where his son is, at one point being knocked back to normal for an instant...
5: ...Transforms back to SSJ2 for the duration of his battle against Buu's thought forms.
6: Inside Buu's innards against the mental Buu, seeing that a blast from Goku at SSJ couldn't even dent Buu's head, Vegeta and Goku together transform and handicap-battle until they're beaten bad enough back to SSJ.
7: When Kid Buu launches his planet-obliterating ball attack, Vegeta quickly transforms to SSJ2 with Goku in order to pick up Gohan, Piccolo, and the kids to teleport from Earth, reverting back to SSJ as everyone is transported to the Kaioshin world.
8: After Goku is battered and reverted from SSJ3 to normal in his first round with Kid Buu, Vegeta very briefly transforms to SSJ2 to fly to Goku's side, however most oddly is reverted back to normal form after landing and for subsequently his first round against Kid Buu.
9: For Vegeta's second round against Kid Buu, in order to stall him for exactly a minute, he transforms to his maximum SSJ2 level, eventually being blasted in the face pointblank back to normal.
10: After Kid Buu thinks Vegeta is beaten, the Saiyan prince surprisingly transforms right back to SSJ2 with hardly any reserves, holding an astounding effort to stall Buu until he's beaten bad enough that he's back to normal (setting the stage for Mr. Satan to stall him).
11: Following the destruction of Capsule Corp. at Hildegarn's power, Vegeta shows up to try his hand, transforming to SSJ2 for a brief battle, reverting back to normal after protecting a building full of people against Hildegarn.
12: While at SSJ during battle against SSJ2 Bebi-Gohan, Vegeta gets into an energy battle with the Tsufurujin, where he transforms to SSJ2 to overpower him and subsequently battle him in that form.
13: To have one more battle of sport against Goku, Vegeta goes SSJ2 alongside Goku on a bridge, but Goku's stomach ache for food gets in the way and the two call it off.
14: Up against Super 17, Vegeta transforms to SSJ2 alongside Gohan and the SSJ transformations of Goten and Trunks, holding up against 17 until beaten back to normal state.
15: In a last stand against Super 17, trying to prove he alone was the protector of Earth rather than "Kakarrot", Vegeta goes SSJ2 in a last defense, but is reverted back to normal after being saved by Goku.
16: Testing himself in an extreme gravity machine while Goku's battling Si Xing Long, Vegeta briefly goes SSJ2, but reverts right back to normal out of exaustion.

That entire list is pretty obviously based from my point of view of the anime canon, so it's very debatable, I guess. That's just how I see the SSJ2 transformation, lightning isn't essential to determine when a Saiyan is at the level as it's more a sign of great intensity (at least in the anime, I'm staying out of business in the manga universe), IMO. I'm not saying that all those moments are correct, they're just correct from my POV, feel free to agree or disagree.

[SS2 Vegeto]

In the anime, Yamcha is also stronger than SSJ2 Perfect Cell. D:

Really, I don't think it's even possible to make complete sense out of everything in the anime.

But, yeah. In the anime they basically turned it into an "I'm powerful, and therefore, spark" kind of thing.

[Kaboom]

But, yeah. In the anime they basically turned it into an "I'm powerful, and therefore, spark" kind of thing.

"I pwn, therefore, I spark."

[Tyro]

Manga SSj2 occurances:

Cell:
1. Post-regeneration from self-explosion.

Gohan:
1. First time against Cell.
2. When "Super Perfect Cell" returns.
3. When showing Kibito his "new Super Super Saiyan form."

Goku:
1. Against Yakon.
2. Against Majin Vegeta.
3. Teaching Babbidi about the forms.

Vegeta:
1. While "Majin Vegeta"; right before fighting Goku.
2. Against Chibi Boo.

[Rocketman]

Vegetto had lightning around him in the manga when he transformed.

[Tyro]

Yeah, I wasn't sure to include that or not, because it was only for one panel. Through the rest of the time he was just a SSj.

[Rocketman]

Yeah, I wasn't sure to include that or not, because it was only for one panel. Through the rest of the time he was just a SSj.

Obviously, the universe could not contain the incredible awesomeness of SSJ2 Vegetto. *nod*

[Duo]

Yeah, I wasn't sure to include that or not, because it was only for one panel. Through the rest of the time he was just a SSj.

Obviously, the universe could not contain the incredible awesomeness of SSJ2 Vegetto. *nod*

That's actually quite true. Vegetto's sheer overwhelming incredible power made it so that all he needed was the normal Super Saiyan to utterly destroy Boo like a rag doll.

He only had lightning around him for the one panel where he powers up. We have other instances of non- Super Saiyans forming lightning so there's no reason to think he was Ssj2.

[Rocketman]

That's actually quite true. Vegetto's sheer overwhelming incredible power made it so that all he needed was the normal Super Saiyan to utterly destroy Boo like a rag doll.

He could've done it in base form. He just wanted to make Buu desperate enough to use absorption. *nod*

[SS2 Vegeto]

I doubt base form, some how. It was stated that he probably wouldn't need to transform against Gotenks Buu, but Vegetto himself was rather shocked that he could so easily outclass Gohan Buu in Super Saiya-jin form, so I don't think it unrealistic to place base Vegetto just a little bit below him.