[Full-Tilt Kamehameha] SS2 Gohan (Youth) is a semi-self-sufficient nuker with high natural stats. One of the strongest and sought after units in the game.
SS2 Gohan (Youth) can fit primarily on two teams, Super INT and "Hybrid Saiyans", but he can also be used on "Potara" and "SS3".
Super INT
SS2 Gohan (Youth) synergizes very well with the other units of his element because of his great links. There are two ways to use him on this team: the first one is to pair him with an orb-changer like [Blade of Hope and Dreams] Super Saiyan Trunks (Future), and the second one is to leave him on rotation with one of the two Outshining Darkness Super Gogeta. His role on Super INT is to be the main damage dealer, SS2 Gohan (Youth) is easily the main star of the team.
"Hybrid Saiyans"
SS2 Gohan (Youth)'s best team is this one, his semi-self-sufficiency is going to help out since [The Second Super Saiyan] SS Trunks (Teen) is also on the team and is going to require some orbs to function properly. SS2 Gohan (Youth) should be left on rotation with an orb-changer to maximize his damage output: one of the best choices would still be SS Trunks (Future), but [Unconventional Fusion] Whirus, despite the fact that he doesn't get a boost from the Leader Skill, is arguably better because he can offer more orbs to nuke with.
"Potara"
On a "Potara" team, SS2 Gohan (Youth) does not suffer from as much competition, the other LR on the team, the leader, is semi-self-sufficient and prefers rainbow Ki spheres, so the two are usually not going to clash with each other. SS2 Gohan (Youth) should be left off-rotation on this team.
"SS3"
What I said for "Potara" kind of goes for this team too, with only one exception: SS2 Gohan (Youth) is a good choice unless you are using [Golden Fist] SS3 Goku , in that case Outshining Darkness Super Gogeta would better as the last unit on the team since he has "Over in a Flash" and "Experienced Fighters". SS3 Goku would prefer to have two units with "Over in a Flash" on rotation to get his 18+ Ki more consistently, otherwise the last slot goes to SS2 Gohan (Youth): the team usually does not struggle with Ki so it's easy to save up a bunch of orbs for him to nuke.
Super Attack
SS2 Gohan (Youth)'s 12-17 Ki Super causes mega-colossal damage and has no additional effect, whereas his 18+ Ki causes mega-colossal damage and raises his ATK by 50% for one turn.
SS2 Gohan (Youth) has a nuker Passive that gives him 18% and an additional Ki per orb obtained. These two together make it easy to get his 18+ Ki Super and make him one of the best LRs in the game.
Link Skill
SS2 Gohan (Youth)'s links are very good: first of all he gets "Fierce Battle", unlike [Beyond the Ferocious Flash] Majin Vegeta. Main Ki links are "Prepared for Battle" and "Shocking Speed", both very solid and common on his teams, with the addition of "Gaze of Respect", which can be activated with most other Piccolo and Gohan units.
Super Gogeta and SS2 Gohan (Youth) share "Shocking Speed", "Prepared for Battle", "Super Saiyan" and "Fierce Battle": with such great synergy most of the orbs on the board can be left for SS2 Gohan (Youth) to take and nuke with.
Being the best support unit for Super INT type, this Gohan (Kid) is possibly the best unit to have on rotation, as a floater, with SS2 Gohan (Youth), providing between his Passive and links shared 7 Ki, 40% ATK and 40% DEF.
Whirus can make up for the loss in damage output with the amount of orbs he can provide for SS2 Gohan (Youth), making 3/5 of the orbs on the board PHY and also activating "Shocking Speed".
As I said before, the best way to use SS2 Gohan (Youth) is to pair him with an orb-changer. SS Trunks (Future) provides INT orbs, making it very easy for SS2 Gohan (Youth) to get his 18+ Ki Super, since these give him 3 Ki each, and activates "Prepared for Battle", "Super Saiyan" and "Fierce Battle".
Hidden Potential
SS2 Gohan (Youth) gets a natural lv.5 Dodge so his max potential in Criticals is going to be 15 unfortunately, a 30% chance. The rest should be invested on Additionals, the unit already has high natural stats to defend himself and is on the tankiest teams in the game "Hybrid Saiyans".
SS2 Gohan (Youth)'s Super Attack can be farmed up to SA 10 through either Gentle-Hearted Warrior Super Saiyan Gohan (Youth) from the Baba Shop with a 100% chance once Z-Awakened, or through Resolute Valor Super Saiyan Gohan (Youth), but only with a 50% chance. From SA 10 to SA 20 Kais are required: the unit will get an additional boost (30%) to his Super Attack multiplier at SA 20.