SS3 Goku heavily limits the choices for the remaining units on this team, and by choosing him you are basically cutting out the best choice for the AGL slot, [Mystery Super Technique] SS3 Goku, since they share the same name, but [Golden Fist] SS3 Goku is just that good, you want to have him on your team if you are taking an “Over in a Flash”-oriented approach. On “Rainbow Heroes”,SS3 Goku is a main rotation unit, ideally put in the middle where he can get the most amount of Ki in order to perform his 18+ Ki Super Attack more consistently.
“Super Saiyan 3”
“SS3” is the best environment for SS3 Goku, it’s the team where he is going to hit the hardest thanks to the 170% ATK boost from [Saiyans Proof of Power] SS3 Bardock ’s Leader Skill and 40% additional from his Passive. The team is filled with Over in a Flash units and nobody in particular needs to get a lot of orbs excluding the LR, so fairly easy to save up some for him to get his strongest attack. SS3 Goku should ideally be put in middle to start off at 12 Ki and he is going to be strongest unit on the team
SS3 Goku’s Super Attacks don’t really have anything special for an LR, his 12-17 Ki causes colossal damage and has a 15% chance to stun and his 18+ Ki causes mega-colossal and greatly lowers DEF.
SS3 Goku is a particular type of leader, he gives 4 Ki to all Super TEQ types and 100% to all stats, but this element is really consistent enough to not need that extra Ki, unlike Extreme INT. You can still run him as a leader for your team and even bring some Extreme TEQ units, since they are going to receive a boost too, if you are lacking options.
SS3 Goku gets a 120% DEF boost at the start of the turn, making him extremely tanky, and then a 180% ATK boost and -70% DEF when launching his 18+ Ki Super Attack. The second part of the Passive is what makes him so strong and also what makes his 12-17 Ki so underwhelming compared to his 18+ Ki: the ATK boost he receives is not applied at the start of the turn together with support Passives, it’s right after his Ki multiplier, resulting in a much higher increase, just like Beyond the Ferocious Flash Majin Vegeta, but even stronger. Support Passives are particularly important in this case, especially since SS3 Goku has only two relevant ATK links, they are going to have a huge impact on his ATK.
Tien is a support unit, he gives Ki, ATK and DEF with his Passive to all Super TEQ types, he shares “Over in a Flash” with SS3 Goku and can also activate “Experienced Fighters”: when Tien shows up on rotation as floater, SS3 Goku can maximize his ATK and activate most of his links. Tien adds in total 6 Ki, 50% ATK and 40% DEF to SS3 Goku, which is particularly important because of the way SS3 Goku’s Passive works.
Tapion is an interesting choice for Super TEQ, he does have “Experienced Fighters” and can also create rainbow Ki spheres, opening paths for SS3 Goku, he is one of the best orb-changers to bring on this team.
Super Gogeta can activate pretty much all of SS3 Goku’s relevant links, with the exclusion of “Shattering the Limits”. These two paired together add 3 Ki and 20% ATK to each other, which is not that bad considering that’s basically all SS3 Goku has.
It’s definitely a blessing that the leader of the team on which SS3 Goku performs at his best can also link up well with him: the two of them give 3 Ki and 20% ATK to each other plus the additional 40% from SS3 Bardock’s Passive when your HP is below 70%.