The game was and is still difficult and grindy. Some difficulty spikes in particular are just fiendish. The first one I can remember was like the fifth mission in the game when you start at the bottom of a hill that is full of enemy archers. If you hadn't spec'd your team a certain way, you'd have to grind for three hours to unlock classes and abilities strong enough to counter them. Also random encounters level scale, which means they're more difficult than the story missions if you stop and grind too many times.
The game difficult scales with your max main character level… so if you are high level the enemies will be high level if you are low level they will be low level.
Stories battles will scale way lower than you main max level while the random battles (when you move in the map) will scale around your max level… so random battle are way more difficult than stories battles.
Another point is that if you stick to one class path for each you won’t need to grind… and remember that the key to win/lose are debuffs and buffs so have supportive characters classes in your team always.
Character specific classes are overpowered too like Ramza, Angrias, Cidilfus, Dellita, etc… they have specific class for them that you should focus because they break the level difficult system (Dellita supportive long range buffs/debuffs are ridiculous to the point to stop even bosses to move or attack) and Ramza/Angrias/Cildifus main multiple rang attack spells are devastators even in end game battles… Cidifuls can play alone battles without any issue… that how game breaking easy it is.
Plus try to focus in different class paths to the others characters that doesn’t have specific classes… Calculator, Time Mage, and even Black/White mages are essential to the party…. Calculators and Time Mages again are game breaking characters.
It is a strategy game and the key for win/lose is how you use your supportive characters… doing that the game is very easy to the point to be mindless easy due the several amount of game breaking classes already in early game.
Some skills breaks the game too like AutoPotions (you don’t need White Mages or Healers anymore) or AutoHaster (basically after some hits you will start to attack several times before your enemies attacks)…
Man… Sunken State, Hamedo, Meatbone, Arrow Guard, TP + Meteor, Calculators, Short Charge, Ninja + Concentrate… any of these will make you auto battle all battles in the game and you will get all these before mid of game just doing stories missions (no grind).
PS. I’m talking about Vanilla FFT… it is easy and doesn’t need grind if you don’t want… the stories missions will level you enough to all encounters… I never played the PSP version so I don’t know if it was changed.
Edit - More I think about it… more easier the game becomes in my mind… it just too many overpowered classes and skills.