"Physical"
Don't try to hit him...
He is immune to physical attacks, as demonstrated here against Wonder Woman's attacks which he handily phases through, absorbs and redirects the kinetic energy back to her:
And though his 'strength' is energy based, Asmodel [a trans-dimensional angel who was beating the piss out of J'onn just before this] doesn't have much success trying to overpower him:
Neither does a Mxy created magical clone of Doomsday:
...he is too fast to hit, anyway
Filtering individual wavelengths and absorbing lightspeed energy from a bomb as time stands still:
Races with Flash around the world at FTL speeds:
Moves so fast Flash has problems recognizing him:
When he was first starting to get to know his powers, he moved FTL and from his perception microseconds were hours:
Explicitly faster than he was previously in his normal form:
Omni-energy absorbtion/Energy manipulation
"Hard light or soft light is still energy - and I absorb energy"
To start the absurdity, Parasite tries to drain him, but Blue Supes is the one that ends up doing the draining:
An alien device that drains the entire planet of its energies [*cough* - *cough*] can't overpower Blue Superman
Traps an ancient alien energy absorber inside himself and begins feeding on him:
He becomes more powerful with every hammer swung and every step Flash takes:
Transmutates electromagnetic energy into geo magnetic energy:
He can casually alternate himself from one type of energy to another:
Manipulated the combined telepathy of J'onn, Tomorrow Woman [whose tp > J'onn] and Aquaman towards the entire Earth:
Blue Superman encounters a guy whose power is to psionically get every power. He wants to imagine a weapon, to be invulnerable, to be stronger than his opponent? He just thinks it, and it is.
Solution? Blue S takes control of his psychic energy, transmutates it and disperses it, depowering him.