While he can give the Team lots of advantages, there are enough drawbacks to make many seasoned Players pass EX DK Piccolo PUR over.
In addition to holding the wrong Arts cards for his Fighting Style, EX DK Piccolo PUR's Ki Recovery Speed is so low that he might as well not have the stat at all. And while one of those Strike Arts Cards inflicts Poison and would be of great use to an actual Melee Fighter, this would require carrying along EX DK Piccolo PUR as dead weight.
But what really makes this Fighter so frustrating is that he isn’t Tagged as a Piccolo variant. The reason for this is from some pretty old Dragon Ball lore. Basically, the Piccolo from Dragon Ball Z is the reincarnation/son of the Demon King Piccolo who existed in the original series. This isn’t just a different story arc--this is a different person who now needs to get some Equips of his own.
This Fighter’s Z-Ability makes him a good bench option for Offensive Teams that need more survivability.
Crippling Ki Recovery Speed
He would likely burn through Ki so fast at the beginning of a Match that he would need to switch out before his Main Ability is even charged.
If that weren’t enough, his temporary Unique Ability is the only one he has. Every balancing measure built into EX DK Piccolo PUR ends up making him unplayable.
Poor Tag Synergy
While a color-locked Z-Ability isn’t a complete disadvantage in the current Meta on its own, EX DK Piccolo PUR’s fate is sealed by how few Purple Fighters are in the RegenerationTag.
Purple Color Counter
Outside of being a powerful force all on his own, EX DK Piccolo PUR doesn’t bring much Support to a Team unless they are Purple.
Since Monochromatic Teams are a risky choice in the current Meta, a viable alternative to this that gives his Z-Ability use is a Purple Color Counter Team. He Buffs two stats--even at 0 stars so at the very least, he's useful on the bench.