Allow me to do the advantages and disadvantages:
Attack: 5pb, see above.
Durability: 5pb, see Attack.
Lifting Strength: Cube. 10>5
Stamina: Cube. Limitless > Average (assuming at default average stamina for 5pb since its listed as unknown)
Range: 5pb. Thousands of km > dozens of m.
Intelligence: Cube. As a supercomputer, that would grant him good knowledge as well as good skill. 5pb is average at best.
Experience: 5pb. Is teen, while Cube is just a week old.
Abilities: Close one, but gotta say Cube. These two have good abilities that can rival each other, both can Amp themselves and Debuff each other, and both have good elemental resistances. While 5pb might resist statuses, she unfortunately cant resist one particular status that Cube can do: Sleep. While you say that 5pb can null that using Sforzando, in actuality, Cube resists that. So, he puts 5pb to sleep, attacks, and GG.
Conclusion: Cube, despite only being a week old, is surprisingly skilled and better stats than 5pb in most categories. By the time he puts 5pb to sleep, its game over. 5pb would not even know that she cant power null Cube, so Cube can tire her thanks to a stamina advantage, put her to sleep, and gg. While he has a range disadvantage, he can tire out 5pb until she is too tired to fight back, then he walks up to her close and does the thing. Voting Cube.
