(NOTE: this math just uses the average weight of an AC not any specific part, because if we use specific parts then there will be be thousands of combinations and thousands of math equations)

YES! A medium-weight Armored Core can hover indefinitely by producing thrust equal to its weight. Given its mass m=10,000kg, the required thrust to hover indefinitely is:


Ft=mg=10,000*9.8=98,000N


so to generate this thrust, the engines need power based on exhaust velocity ve:


P= (Ft*ve)​÷2

​
With ve=1,000m/s, the power required is:


P= (98,000)÷ 2*1,000=49,000,000W=49MW


So yes, a medium-weight Armored Core would theoretically hover indefinitely but only with an energy source that can supply this power continuously will successfully allow the Armored Core to stay airborne indefinitely.