Best teammates for Ayra?

Lancina.

Brave Ike, Dorcas or a green mage like Rjahat, Sonya, Nino, Deirdre (your preference) / someone that can take out Reinhardt and other blue mages that threaten her. She’ll also struggle against blue walls like Effie and Lukas, so whoever you prefer in the green powerhouse/mage slot.

P Azura is good for her also.

I pair her with Soren who checks blues and also has Hone Speed, and rotate between B!Lucina and Delthea for extra buffs. Fourth slot is usually a Bow Lyn check.

My Ayra is with B!Lucina, B!Ike, and Inigo(Rein/Bow check).
Pretty much my best team.

My current team is:

Ayra (DC, QR3, SpdSmoke3, DistDef3/Ayra's Blade/Reposition/Aether or Regnal Astra)
B!Ike (Steady Breath, Beorc's, PP3, Brash Assault 3/Urvan/Pivot/Aether)
Lancina (Fury 3, Renewal 3, Drive Spd 2, Spur Def3/Geirskögul/RecipAid/Aether)
Inigo (TA3, Bowbreaker3, Drive Attack 2, Attack Smoke 3/Gronnraven+/Dance/Luna)

This team has been steamrolling EVERYTHING. for TT, I'll use Aether on the three melees for sustain, while Lancina acts as a pseudo healer and buffer. Inigo can check all colourless and blue mages, while Ayra can handle all green mages and non-buffed red mages on defence. B!Ike is the sustain tank, and can take and heal up from any non-red, and can usually take one defence encounter with a melee red, especially if Aether is ready to proc.

I used to barely make it through Lunatic 40 TT's with four teams. With this one, though, it's rare I lose any of these units at all.

Ayra Lancina Fem!Robin and Genny do rather well since Robin Laughs at +10 Reinhardts and Lancina buffs Ayra and Genny can heal or attack