Not a perfect run. Could've done a lot better.

Definitely possible and not that difficult (unless you just started playing)

The Team^details

Couple of things that would've improved this run...

• I should've grinded out more Esper Stones so I could summon Diabolos once and get Maxwell.
• Destiny hit Exdeath even though Charlotte provoked... Damn RNG.
  Here's Charlotte after taking a Destiny barely hung on but I didnt guard because this was one of the random ones Maxwell does at low HP.
• I didn't pay attention to the thresholds. I heard she was weak to magic but damn...
  This OP Exdeath did way too much and passed right into Endless' range. Because of that he died but if I triggered it with Laswell instead and guarded Exdeath he'd have been fine.

Those last two points cost me the No Death achievement.

That's about it. Krile and Sakura never even came close to dying tbh. 4K HP was probably unnecessary, 3.5 might do fine. It's really only needed for units carrying Diabolos. Rain and Sakura are free, Krile is a very common summon. So for your friend you'll want either a powerful black mage or a bulky tank.