[Martial Artists Fight] Goku is a decent unit, he can stun and even tank pretty well after launching the Super Attack; the damage output is nothing amazing, but it's still pretty good, and the unit does have some interesting links that can help him fit on a Super PHY team.
Good tank Decent damage Stunner
Lacks common ATK links Low stat boost (B Rank Potential System)
Supreme damage is nothing special, but at least the unit has other ways to increase its damage potential and the 12 Ki multiplier is 140%, which is pretty good; the Super Attack has a 30% chance to stun that makes this unit pretty good in terms of utility.
No boost to HP and only 2 Ki, but 60% to ATK and DEF is not that bad for as Sub-Leader SKill for Dokkan Battlefield, if you lack units.
Getting an 80% boost to ATK and DEF when performing a Super Attack is sort of double-edged sword: the unit will not be able to tank before launching the Super Attack, but, since Goku is going to be a floater, he will only be attacked after he receives the boost; the unit will receive a much greater boost if support is on rotation, but, again, if Goku is a floater, he will likely not benefit from this.
How good is this Passive Skill?
In a realistic scenario, Goku will be in the last slot and no support will be on rotation, meaning that at 55% in the Potential System on a Super PHY team, his DEF will be at 20.379 before the Super Attack and at 36.683 after it, which is already a very good value. Now if we want to create an ideal scenario, we would have to put him on rotation with the support Gohan I mentioned before; this time his DEF will be at 32.811 before the Super Attack and at 59.060 after; this amount of DEF is more than enough to qualify him as a tank, he will probably take less than 20k damage from normal attack in Super Battle Road, which is quite a feat for any defensive unit.
Gohan (Teen) doesn't share any Ki links with Goku, but his support Passive makes up for it providing him with 3 Ki and a 40% ATK and DEF boost; in addition to this, Gohan (Teen) activates "All in the Family" for an additional 15% DEF, giving Goku a third multiplier.
Pan (GT) does not share any Ki link with Goku and her Passive doesn’t add anything in that department, but she can activate “All in the Family” for a 15% DEF boost and “Kamehameha” for an additional 2500 flat ATK; Pan (GT)’s Passive gives all allies a 30% ATK and DEF boost, partially making up for Goku’s overall lack of ATK links and further enhancing his defensive capabilities.
Great Saiyaman 2 is a very good unit that is also pretty easy to obtain; she is going to give Goku a 40% DEF boost with her Passive and also activate “Infighter” for a 10% ATK boost.
Additional Attacks are nice to raise the chance of stunning the opponent, but Criticals will always be the best way to go in order to maximize the damage potential; the unit has a B Rank Potential System, meaning the average stat boost at 100% is 3000 instead of 5000, thus I would not advise putting orbs into this unit as the value you will get from doing so is not much.