First only a part of the whole army was well equipted - the elite army of ROC trained and supplied by Germans. The rest was kind of garbage without amored vehicles and lack of combat aircrafts. Surely they stand no chance against well equiped, heavy amored Japanese Army. Plus they have the a enormouse advantage with their all kind of aircrafts gaining air dominance. Its quite a impossibility to have a victory against such superior army.
With "heavy armoured", you mean that the IJA has plenty of heavy tanks and other effective armoured vehicles at its disposal? No, it can't be. All in all, the Japanese tanks were mediocre at best, but the NRA suffers from a chronic shortage of armoured vehicles and anti-tank weapons itself, so even obsolete tanks soldiered on in China in the IJA until the very end of WWII. Lend-Lease American tanks in NRA service did show remarkable success in Burma however, as well as the efforts of the 200th Division, the first mechanised division of the NRA which received Soviet tanks, small arms and ordnance.
Generally speaking, most of the Nationalist divisions were understrength (for standards in 20th century warfare), lacked artillery and received little to no training with the notable exception of the German-trained divisions as you've already pointed out and the Muslim ones which were trained without Western aid and was devoid of modern weaponry, but impressed European observers with awe.
As far as the Air Force was concerned the ROCAF received substantial Soviet, and later American support with overall indifferent results even though some success could be attained.