Piccolo Jr. (Giant Form) is an interesting unit, he can lower the enemy's ATK with his Passive, he can stun the opponent with his Passive and he has a chance to turn into his "Giant Form"; the main use I see for this unit is on Extreme STR for Super Battle Road, where his debuff can be stacked with Hopeless Minus Energy Omega Shenron's Passive, but he could also be used on a Giant category team.
When the passive of Piccolo Jr. (Giant Form) activates
Super Explosive Breath Cannon
Causes destructive damage to enemy
12 Ki Multiplier
In Giant form, Piccolo Jr. won't take any damage
Giant Namek Mode
Strategies & Tips
Teams and Role
Piccolo Jr. (Giant Form) can be a solid option as a floater on this team; between his Passive and Omega Shenron's 30% ATK debuff, you will be able to reduce incoming damage by 50%, which can be quite nice in certain game modes. In terms of links Piccolo Jr. (Giant Form) doesn't have that much synergy with his own element, he lacks common Ki links and he will likely struggle to get a Super Attack off, but at least, being a floater, he is more likely to have Big Bad Bosses active by the time the enemy will attack him.
Piccolo Jr. (Giant Form) does share Transform with most of the other units in the category and there are some good Extreme type units that can help him activate Big Bad Bosses so he fits relatively well on this team, but his damage is still pretty underwhelming, even under a 150% ATK Leader Skill; his best trait is his ATK debuff, which is going to help out the Leader of the team, [Sleepless Hero] Tapion (Hirudegarn) tank better, so Piccolo Jr. is going to be a floater, just adding utility and some Ki.
Supreme damage and a 140% is pretty average, Piccolo Jr. (Giant Form) is not going to be able to deal that much damage.
As a Sub-Leader, Piccolo Jr.(Giant Form) is not too bad; 2 Ki and 60% ATK and DEF to all STR types can be used, even though it's nothing amazing.
Piccolo Jr. (Giant Form)'s Passive is the main reason why you would want to run him; a 20% debuff with no restriction is really good and stunning through the Passive is better than having the mechanic bound to the Super Attack; being able to transform is not a particularly good mechanic, even though the invulnerability for a few turns can be nice to get some damage off for free in Super Battle Road.
Big Bad Bosses and Transform are the only noticeable links this unit has; Shattering the Limit is not commonly shared among Extreme STR units and the rest of this unit's links are pretty much useless, being so niche.
Omega Shenron and Piccolo Jr. (Giant Form) share no Ki links at all, but they can activate “Big Bad Bosses” for each other can their Passives do stack together; the enemies’ ATK will be halved when these two units are together on rotation.
Full Power Boujack shares with Piccolo Jr. (Giant Form) “Shattering the Limit”, which, as I said, is not that common of a link among Extreme STR units; these two units can also activate “Big Bad Bosses” for each other.
Both of these two Goku (Youth) (Giant Ape) share “Transform”, “The Incredible Adventure” and “Shattering The Limit” with Piccolo Jr. (Giant Form) for an automatic Super Attack and they can activate “Guidance of the Dragon Balls” for a 20% ATK boost.
Vegeta (Giant Ape) shares both “Transform” and “Shattering the Limit” with Piccolo Jr. (Giant Form) while also being able to activate “Big Bad Bosses” when the HP drop below 80%.
The Potential System is what kills this unit, you don't get much value at all from investing orbs into it, so I wouldn't advise wasting STR orbs even if you get multiple copies of it.
Should I use Elder Kais/Grand Kais?
While it's true the damage output of this unit while in "Giant Form" form, will increase if the Super Attack Level is maxed out, it's not enough of a reason to invest Kais on it; the Super Attack of Piccolo Jr. (Giant Form) is not farmable and there are a lot of better STR units to feed Kais to.