I have some good laughs reading these last weeks...
the idea that Romania would attack Hungary is one of the silliest things I've heard lately. There is absolutely no reason for that to happen, other than, say, Hungary allying with Russia and attacking NATO or the European Union.
Likewise, an attack by Hungary, even equipped with all the armor in the Zrinyi program, would again be very fanciful. Romania would have 2 brigades in the West, could bring another brigade from Oltenia and wouldn't even have to move the special forces brigade from Targu Mures or the mountain troops in Szekelyland. A Patriot battery, a squadron of F-16s and a battalion of Himars would be enough to keep the two Hungarian army in check; in fact, the moment your only armored brigade would attack, Hungary would become so vulnerable to the maneuver of at least 3 Romanian brigades in the area that it could still be over in a month. This would keep some infantry brigades plus the tracked ones in the East without need to move them. Add to this the new units which will be formed in coming years.
The only plausible scenario in which your armored forces would fight would be alongside a Romanian, a Slovak and a German brigade, probably under German command, somewhere east of the Carpathians, in Ukraine, to defend NATO or the EU from Russian aggression.
The Romanian army has a very important thing and that is the experience (even limited in conflicts like Iraq, Afghanistan) in last 20 years and in comparison the Hungarian army has not fired a shot in war conditions for 80 years or even more; add to this about 20,000 reservists rotated in the above-mentioned conflicts and about 50,000 Gendarmerie troops who receive military training and gear.
There are a lot of prejudices written here, some about the level of preparedness, others about different allies (the Serbia thing is just the fantasy of some nostalgic Ceausist), for your own good you should pay a bit more attention to what is happening to your east because despite the proximity there is so much false information.