Chain Challenge Struggle

Well the most essential part of tempest trials is having a healer, and that Genny will probably serve you just fine, as for the other three, Caeda and Clair are great together for having great matchups against alot of units you may find in chain challenges, and if your spring camilla is a gronraven mage, then she can deal with the archers caeda and clair cant go in and 1-round. Otherwise, fallen grima is another great choice for a archer tanker, you just might want one of the two Pegasus knights to equip a guidance seal to help him out.

Dragons are always good for their bulk and distant counter breaths but you'll also need at least one player phase unit. It's hard to recommend a team without knowing IVs and skill of all your units but you'll know who works well together. Brave Ike with his base set is a very good option as well as he can tank and self heal, I use him on my main team so I know he workS well. Also remember to Ally Support your team as those extra stats can make all the difference sometimes.

Whatever the team, I'd suggest setting Marth up as a combat medic with his Falchion, refined preferably, and Renewal 3 and Ardent Sacrifice/Reciprocal Aid for healing the team (I use my Summoner Supported Lucina for this).

Genny with dazzle gravity/pain will serve you well in chain challenges.
I typically run 2 dancers and Rein/B.Lyn for the lunatic modes.
My backup is usually 2 other dancers, Genny (with savage blow 6), and either a repositioner or a DC vantage unit (Xander/Camus)