I'm not deep in the character stats systems, so I can't offer
too much help there, but here are a few things to note about the main battle systems to pay attention to in the early game if you're switching from Xenoblade:
- Art colors are changed up a bit; red is generally assigned to melee arts, yellow to ranged arts, blue to Auras, green to buffs/healing, and purple to debuffs. It's good to give most characters a mix of many different kinds of arts.
- When a teammate calls out advice mid-battle, look at the color of the text box and use an art of the corresponding color to trigger Soul Voice. This will trigger a certain kind of effect (heal party members, topple enemies, etc.) depending on what the character called out. Your character will occasionally call things out for the other characters to respond to as well.
- Toppling is still a thing (briefly disables an enemy/allows you to do more damage), but it isn't assigned to an art color; look at the descriptions of each art to see which ones can topple. There's a related status effect called Stagger (similar to Break from the last game, can be inflicted by certain arts/Soul Voices) that makes it easier to topple enemies. There's no Daze equivalent this time around.
- You can destroy enemy appendages this time. There's a small circle gauge that appears next to enemies when you aim at them from certain angles. This shows how much damage it'll take to destroy that appendage. Destroyed enemy parts usually give you materials and sometimes weapons when you defeat the enemy.
- Switching targets is really wonky compared to the last game; I haven't figured out a way to get around this.
- The game really strongly encourages you to chain arts in certain ways this time around. When an art says it's boosted by being part of a melee/ranged "combo," it means the art will become more powerful when used as the follow-up to an art of the specified type.
- Each character has a class, with assigned ranged/melee weapon types for each class. Most characters start with a predetermined class, but you can switch your main character's class at any time, and there's a class tree for your character (with three main branches). You get different arts as you level up each class; some arts can be carried over between classes.
- You can (and should) level up arts. Go into the Party -> Arts menu and highlight any art icon with the cursor, then press X. You'll have to spend Battle Points (BP) to do this. It typically makes them stronger/extends the duration of their effects, just like in the old Xenoblade.
- You can also gain passive effects from boosting your classes, called Skills (similar to the Affinity Skill Trees from the last game) that can also be leveled up with BP (also by highlighting the skill's icon with the cursor and pressing X) to improve their effects. Make sure you stack all your characters with skills that are suited to their role in battle/the enemies you're up against.
- Augments replace Gems in this game. Most gear comes with its own preset augments (which can vary between each piece of gear, but can't be changed), but sometimes gear will have slots that you can add your own augments to. (Highlight the gear in the menu and press X.) You can also level up the augments attached to your gear by using up monster parts (letting you get Ranged Attack VI augments pretty early on instead of at endgame/only by using the gem furnace like in the first game).
- In general I've noticed that preset augments will often offer boosts that outweigh the standard stats benefits that come with equipping higher tier gear, although this might not be so prevalent once I get gear with more slots/more augments to stick in those slots.
Those were most of the huge adjustments to the battle mechanics for me. I'm still not really that concerned with lots of the stats (I don't even know what Potential does atm honestly) but if I run into a major difficulty wall I'll start prying open the hood like I did in the first game.
edit:
1. Make use of secondary cooldowns. On the art screen you can see what effects the secondary cooldown has. Usually it increases damage/ effect, lets you use it again immediately, or other stuff.
You can spot this by looking for a green circle bar that fills in once an art is available to use. It'll usually only fill while you're auto-attacking using the weapon of the corresponding type (melee or ranged).