I'm managed to get my party to level 99 before starting new game +, but the new dungeon is destroying me.
I wonder if all jobs need to be levelled up? And not just the ones I use.
So Amon's towers are interesting, they are difficulty independant. Having finished EX hard:
The normal Amon tower which unlocks when you first finish the game doesn;t increase in difficulty on EX Hard - which means its actually the easiest part of the game to play on EX Hard as everything does so little damage - yet EXP and rewards are great because its basically a endgame dungeon. So that's useful.
The new Amon tower is geared toward people who have finished EX Hard. And even then, its hard, which makes it the first difficult thing in the series for over a decade. So that's nice! In order to tackle Amon's Super Tower you'd want to be completely max leveled with job and base level, and seemingly have really good gear which boosts your health to 2K-2.5K AT LEAST - this is the bit I'm stuck on, I've seen one vid with a dude that has incredible stats but I'm unsure how he managed it. I really need to figure it out as I can't even clear floor 2 in the EX Hard tower yet!
EX Hard in general is fantastic fun though, you can't let your guard down for a second because as of chapter 3, enemies can one shot you (if your really low level, sounds like your fine in that regard) or finish you off in 2-3 hits. And this balances throughout the game so it makes the beginning feel harder because later in the game you'll be rocking better stats and enemies will only get weaker! (slightly).
Keep in mind you keep all your weapons and money, but for your team you'll need to redo their friendship quests including the business management stuff to unlock and max affinity Eri. Now the thing with these friendship missions if you recall is that the final part are missions with you and said friend against a group of enemies - which obviously is way harder now. So for Namba (where its just you Vs a group of goons), Han and especially Zhao (who has Mabuchi show up) are very challenging. Basically unless your rocking high level summons and/or orbital lasers forget about it!
Speaking of which, once you clear the GBH side story (which you have to do in order to progress the story) you unlock every summon you previously had. So in my case I'm rocking everyone from about chapter 5!
The best general strategy is to just focus on your favourite jobs (Saeko has gotta be Idol though) and then build a team up around those. Focus on just the one job and make sure you level those up. Now while XP rates don't change between difficulty levels, job XP does, significantly. The basic gist of it is that its based on the number of enemies in a group, not the level of enemies determines how much job XP you get. So a fight against one of those strong enemies? Its a super long drawn out fight with almost no XP. But a fight against 5 lowest level enemies around the slum areas of Ijincho? 80-100K job XP right there! Utilise this to level up as much as you can.
The rest is just down to perfecting your parry timing, using Saeko and/or Namba to debuff enemies and heal the group, while dudes like Ichiban, Adachi etc. hit hard. Bosses actually feel like they get less health because you hit harder, however they obviously hit hard. But keep in mind those early level bosses hit about as hard as the late game ones, aside from a couple of specific moves so don't worry too much about a difficulty spike at the end.
I think that should basically sum it up. Also keep in mind that on EX Hard, using the money girl summon in floor 30 of the arena gives you 10mil+ per play. Its the quickest way to make money once you reach that point.