Flay Mayweather
Superstar
Broly's physique makes zero sense and doesn't adhere to the rules established, that's why he aint ever gonna be canon. You can't be ultra brolic and be able to move fast, that's why "Super Trunks"(essentially Broly) couldn't touch Cell despite having more power than him your power drains faster and you lose speed, that's why Goku had to specifically learn the SS2 where you don't get extra mass and bulk after the transformation.
Broli was born powerful unlike Trunks.
His body is able to maintain his power without drawbacks