Having so many good Super INT units with Over in a Flash currently in the game, it's kind of difficult for SS3 Gohan (Teen) to really find a place on this team. Super Gogeta, SS3 Bardock and [Super-Dimensional Instinct] Goku (Ultra Instinct -Sign-)are all better options than this unit for the INT slot, but that doesn't mean that SS3 Gohan (Teen) can't fit on this team. This unit should be a floater on this team, linking with [Golden Fist] SS3 Goku when he appears on rotation and activating Experienced Fighters, SS3 Gohan (Teen) will be able to perform very well in terms of damage output.
"Hybrid Saiyans"
Having Over in a Flash as his only Ki links definitely limits SS3 Gohan (Teen)’s usage on this team; he doesn’t link particularly well with any of the units that are usually on rotation due to his lack of Prepared for Battle and Shocking Speed. Under [Hidden Power Unleashed] Ultimate Gohan’s Leader Skill SS3 Gohan (Teen) can be a very powerful unit, taking advantage of the higher DEF boost in order to be able to take hits better.
"SS3"
This team doesn't really have much trouble in terms of Ki, every unit, with the exception of [Mythic Evolution] SS3 Broly, has Over in a Flash, a 3 Ki link, and a lot of units also share Experienced Fighters with SS3 Gohan (Teen). Receiving an additional ATK boost when launching the Super Attack on top of the one that comes from his Passive when SS3 Bardock's Passive is active will equate to an incredible amount of damage and having a 6 turns restriction on his ATK raising mechanic makes it possible for SS3 Gohan to stack it even as a floater.
Super ATK
SS3 Gohan's Super Attack causes supreme damage and gives him a 50% ATK boost on his multiplier, which starts at 380% at SA 10, that lasts for 6 turns. The 12 Ki multiplier is 140%, a good one for a non-Dokkan Fest unit.
Leader Skill
The Leader Skill is nothing amazing, but SS3 Gohan (Teen) can be used a Sub-Leader for Battlefield 2.0.
Passive Skill
SS3 Gohan (Teen)'s Passive gives him two ATK boosts in different moments, a 60% at start of turn and a 60% when performing a Super Attack, these two to not stack additively but multiplicatively: it's not a 120%, it's a 156% boost. The 60% to DEF also allows him to take hits decently well, especially on a "SS3" team under the 170% DEF from the Leader Skill.
Link Skill
SS3 Gohan (Teen)'s links make him fit very well on Super INT, “Rainbow Heroes” and Super Saiyan 3, but he really only has one Ki link if we exclude The Saiyan Lineage, which only gives 1 Ki. Experienced Fighters is now more common among top-tier units, so it’s a good ATK link to have. If this unit Dokkan Awakens through Story Event medals and gain Shattering the Limit, it will actually make him one of the best units for the Super Saiyan 3 team, basically giving [Golden Fist] SS3 Goku an automatic 18+ Ki Super Attack when he is on rotation; if this unit gains Fierce Battle, it will make it even better offensively.
Super Gogeta and SS3 Gohan (Teen) share “Over in a Flash” and activate for each other both “Super Saiyan” and “Experienced Fighters”; the fact that SS3 Gohan (Teen) links well with the Leader of the Super INT is definitely good.
SS3 Bardock and SS3 Gohan (Teen) share “Over in a Flash” and activate for each other “Super Saiyan”, “Experienced Fighters” and “Limit-Breaking Form”; in addition to this, SS3 Bardock’s Passive will greatly boost SS3 Gohan (Teen)’s ATK since the latter receives an additional ATK boost upon Super Attack.
This SS3 Goku is a support unit that gives a 33% boost to both ATK and DEF and can activate “Super Saiyan”, “Experienced Fighters”, “Limit-Breaking Form” and “Saiyan Warrior Race” for SS3 Gohan (Teen).
These two units will likely become the best linking partners if SS3 Gohan (Teen) receives a Dokkan Awakening through non-Dokkan Event medals; so far they share “Over in a Flash” and activate “Super Saiyan”, “Experienced Fighters” and “Limit-Breaking Form”.
Hidden Potential
SS3 Gohan (Teen) can be a pretty tanky unit, he doesn’t need anything more than the natural lv.5 Dodge he gets for being an INT type. The focus should be Critical, as always, but it’s true that this unit receives a huge ATK boost upon Super Attack, further investment in Additional is not a bad idea.
Should I use Elder Kais/Grand Kais?
SS3 Gohan (Teen) does not have a farmable Super Attack, but he is a unit worth bringing to SA 10 with Elder Kais/Grand Kais. If you have a Super INT, “Rainbow Heroes” or Super Saiyan 3 team and you are planning on running him, invest on his SA.