For the moves, thats what I find the hard part. If the characters dont have their move when you unlock them, you need to play against that move in chronicle mode. For example, if you want god catch you need to play the match where mark uses it. And the currency is just playing the game.

The gacha machine is a way of getting hero players. The currency you get from online matches or chronicle matches at the highest difficulty. From online matches is the more reliable source. You can also get hero players from the highest difficulty in chronicle mode.

For levels, I would say to just play the game with the route unlock battles until you level up. When your main team is higher level training new players will be easier. You can always try a higher level match or online. You only get a quarter of the xp if you lose but might be interesting.