Team building

Generally how I build teams is to figure out how I want to play them first.

For examples in your lineup; you could go a physically tanky comp with Ike, B!Ike, and M. Robin for magical damage. You wouldn't have much in the way of resistance in that team, so you could bolster that with Genny to keep them alive and to be your RES stat tank, as long as you are confident in her survival.

Or, if you are looking for one-rounding kill power, you could go for a team of Tharja, Raven, Cordelia and possibly P!Olivia. It wouldn't be able to survive much, but as long as you can initiate and retreat out of range you should be good.

It really depends more on what your goal is in each round. Is it bait and punish? Mobility and damage? Sustain? Etc. Check out what each unit is weak to and what it's good at, and then either create a team to take care of it's weaknesses or to bolster it's strengths. Ex; Tharja and Olivia's Buffs go together well, QR Ike likes Genny's heals, Mae likes a deathball-style gameplay with everyone close together to make the most optimal use of Blarowl, etc. Hope that helps!

For now tharja/ayra, bike, mae and olivia can be ur main a team

Ike repositions ur teamates to safety and tanks.
ayra(tharja) can set up easily with for desperation due to good mixed bulk and can be ur mandatory speedy unit.
Mae can i recommend a desperation brash assault on her rather than renewal. Maybe even vantage with distant def/deflect seals if u REALLY want to capitalize on her owl tome and be able to bait both rein and blyn but would require summoner support.
And olivia to provide support.
This team relies on ike to tank, and ayra and mae to nuke things and with the help of polivia ko enemies then draw back to safety.

Raven, nephenee/cordelia, ike, tharja/genny can b ur b team.