Tips for Leveling Up Unused/Underleveled Characters During the Endgame

[Randoman]

I feel like this warranted its own thread since I've seen this issue brought up multiple times. Anyways...

What are some effective tips/strategies for leveling up characters that were underused/underleveled during a playthrough? For example, a fair amount of players (myself included) benched Anna, not knowing about her skill which is really helpful for money farming. However, she's still a level 5 axe fighter, and is too weak to get any kills or even efficiently level up for the endgame section, especially with skirmishes being way too powerful for her to beat or level grind with.

The best strategies I can think of is to use the Micaiah Emblem ring and have them level up as a healer. The Tower of Trials is out of the question, since it only gives experience after all 3 battles (even on Normal-Casual), and the more leveled up your main team is, the less experience The Tower of Trials give if you set the difficulty down (to the point they'd only get 5-9 experience or less after all 3 battles, which is definitely not worth it).

This is kind of related to the topic as well: I'm thinking of creating a brand new file where I level up all characters equally enough (with tons of skirmish battles), so that even when I reach the endgame, I can still feasibly train them through advanced level 20 skirmishes. Is this is a feasible approach to negating the issue of removing the difficulty of training everyone, or are there any issues/drawbacks to this strategy? (Eg: skirmishes will be much more powerful for even my main team if I level up every character equally)

[Armchair General]

The main drawback with farming skirmishes is that they'll progressively get stronger, no matter what you do

[Original Alear]

The best strategies I can think of is to use the Micaiah Emblem ring and have them level up as a healer. The Tower of Trials is out of the question, since it only gives experience after all 3 battles (even on Normal-Casual), and the more leveled up your main team is, the less experience The Tower of Trials give if you set the difficulty down (to the point they'd only get 5-9 experience or less after all 3 battles, which is definitely not worth it).

Doesn't your character just have to survive the tower of trials? Why can't you just sit them in the corner for all three matches and have them get the reward exp at the end of it? I think I've seen recommending that already. However, micaiah emblem ring might be faster.

[Scaramuccia]

Training skirmishes are an option - you just need to survive it to get bonus xp in the end. But Micaiah and especially Great Sacrifice spam is the best leveling option.

[lenticular]

This is only theorycraft and I've never actually tried it, so standard caveats and disclaimers apply.

But would it be possible to use the Mercy skill from the S rank Elincia bond ring? That would let you consistently get enemy units down to 1hp, at which point even the lowest level unit can happily take them out (with the help of chain attacks if necessary). This could be done alongside the Micaiah/Great Sacrifice idea, and I would guess it would speed things up somewhat.

[BloodRonin]

As someone who has played exclusively on maddening mode, I will give you tips I found useful to get those lower units leveled up. 
First off, the Byleth skill Mentorship is so good when stacked. "Grants 1.2× EXP modifier to unit and adjacent allies" To add, if you have the DLC, the 3 houses units give a skill to grant another 20% exp earned. 

One thing I found super useful is to find a way on maps to always kill the adds that spawn (unless they are the no exp adds). Some characters will clearly be a higher level than others and most likely overleveled. Bench them when you can and add the weaker units it. If you are just going for 1 character to level, simply having Micaiah on them, and have your other units stand in fire can really add up easy exp with staff uses and great sacrifice. (remember, if your units are stacked you get even more exp from the Byleth skill)

Arena gives little exp on maddening, but with the double exp skills mentioned above, I am still able to get half a level or more if I win the matches every time I go back to the hub. Another easy way to farm exp (which I consider cheese) Is when you know your units won't die to a boss, simply corner him or put 4 units around them. Have a staff user spam obstruct, or simply spam heal. 

If you are leveling a ranged class or one that has access to range, (if your case Anna and you don't have staff access) Give her a hand axe, with the Erika emblem, she should be able to get at least 1 damage on an enemy because of the true damage added from the emblem itself. Spamming attacks with her while another unit heals your allies (assuming the boss won't attack at ranged to kill anna) can easily add up exp.     I was able to level my Celine (who was level 8 base class) to level 17 Vidamine in a couple chapters.    I also though, did purposely leave some paralogues in order to level up weaker units later on. 

[Taho]

Byleth's Goddess dance also works. If you dance for four units, you get a significant amount of XP, especially if you combine it with the aforementioned Mentorship. Then you can go to a blue circle thing, recharge, and do it again, while your buffed up units hold the fort. Not sure it works as well as with Micaiah, but worth a try.