I do get what game freak is going for with Pinurchin's stat distribution. IRL Sea Urchin's aren't fast, with a speed of 10 feet per hour. Their armored but frail stat distribution reflects how most of their body is spines with a relatively small fleshy core. Their offenses... while spines can hurt, but as far as I could find, there isn't a sea urchin that uses electricity offensively.
However as Shuckle as proven time and time again, armored but frail rarely works with Pokémon. Dusclops and more recently, Galarian Corsola were probably the most successful, and even then, they both have much higher defenses than Pinurchin. Pinurchin does have decent attacking stats, with its STAB being pushed to respectable thanks to Electric Terrain. However Pinurchin falls into a Jack of All Trades, Master of None role. Good defenses, but belied by horrid HP and lack of resistances preventing it from taking many hits. Good offenses, but not excellent, requiring boosting to truly be good. And all wrapped up in on of the worst speeds in the game. Seriously, getting outsped by Ferrothorn is quite impressive.
Cursed Burr
Pinurchin
Ability: Electric Surge
Item Attached: Leftovers/Lum Berry/Life Orb
-Curse
-Zing Zap
-Liquidation
-Recover
EVs: 252 HP / 252 ATK / 4 SDEF OR
252 HP / 4 ATK / 252 SDEF
Nature: Brave (+ATK, -SPE)
Curse Pinurchin set. Curse to shore up Pinurchin's good attack and defense and go on the offensive. Zing Zap is a great physical STAB, while Liquidation gives that all important coverage against most Ground types. Recover gives Pinurchin the longevity it so desperately needs, enabling it to survive setting up without being totally compromised after.
Leftovers gives further longevity and Pinurchin isn't forced to Recover as often. Lum Berry protects against Burns and Toxic, while Life Orb further shores up Pinurchin's power. Either go for Max HP and Max Attack so that Pinurchin is completely reliant on Curse to do damage and can take further advantage of Electric Terrain, or go for Max HP and Max Special Defense if you want the best chances of setting up, at the cost of having to do more Curses.
Pair with a Trick Room user for maximum effect.