Been spending my energy working on Sheratan, but I did 3 runs of the mermaid event and it worked alright for me. Only had the tutorial msg pop up on first login too (been playing on Nox today, not much on my phone).
I finally beat hard mode Sheratan with the two important missions for moogle/staff/materia. Failed the under 20 turn mission for 2x tickets because I screwed up my team swapping and wasted a few turns getting the fight back on track as a result. Exact lineup I used was:
Main team:
9S -- primary DPS (Pod153 fire chains) -- also 54% fullbreak LB
Rikku -- 2nd dps w/ Pod153 fire chain -- also re-raise LB
WoL -- tank and backup atk/mag breaker when 9S didn't fill his LB by 3rd turn
Tilith -- fullheal every round
Ace -- mana regen and aoe -75% fire imperil
Bench:
Rydia -- came in on the last round for the esper finishing blow
Orran -- came in for one round to deal dark+earth damage (mission)
Fryevia -- turn 1 atk break (-50%) then sat on bench
Ling -- came in for her AoE def/spr break for pumpkins then died and got swapped out
Gilgamesh -- glass cannon setup, came in when pumpkins spawned and AoE capped my chain to 1 shot them (then died)
Video of my clear:
Sheratan Hard Mode -- I think I yelled (excitement) at some point in the vid, sorry if it was loud...
So the way the fight went: Turn 1 I did 50% mag and atk breaks with 9S / Fryevia, Rikku did a pod153 shield, Tilith did a stat buff, WoL provoked (golems because it lasts 3 turns). Then I fat fingered the team swapping and wasted like 3 turns getting Orran into the team with an imperil up so I could do the earth/dark mission.
Once the dark/earth damage mission was done I worked down the boss with 9S and Rikku chaining Pod153, making sure Rikku's re-raise LB was up for thresholds (80/60/50/40/20%). When the pumpkins came out, I made sure my important team members had re-raise the previous turn, then I went pure glass cannon on the pumpkins: Ling did aoe def break, Ace did aoe imperil, then Rikku / 9S built a chain with pods and Gilgamesh capped the chain with Snowpetal, which both one shot the pumkins and pushed the 40% threshold all in one.
Pumpkins died and boss did his 40% threshold attack, which wiped out Gilgamesh and Ling, but the rest had re-raise so they came back, I swapped back in WoL and Tilith, then slowly worked down the boss again (making sure re-raise was up for 20% threshold). When the boss was low, I built a chain with pods and let Rydia cap the chain with Ramuh, mission accomplished.
10 man trials are a ton of fun, I can't wait for the next one!