Highlighted weapons are free options.
On-Field Mavuika focuses on dealing large amounts of Pyro damage while riding her motorcycle: Flamestrider.
She's best played in a team with Cryo characters where she can reliably get up close with Flamestrider and trigger Melt, or she can trigger Vaporize specifically with Furina, Yelan or Mona.
Mavuika relies on a character exclusive mechanic known as Fighting Spirit. Due to these specific mechanics, Mavuika is also best paired with another Natlan character, with the ideal options being Citlali and Xilonen.
Mavuika can also take a more supportive role where she uses less field time and instead helps other DPS with her off-field damage and Pyro application, plus A4 passive giving the onfield unit a potent dmg% buff. Due to her passives, she would still like to Burst in teams where she can reliably gain a large amount of Fighting Spirit both for her damage and buffing capability.
In almost all situations Mavuika will prefer an Elemental Mastery Sands over an ATK% Sands, unless she is not used in Amplifying Reaction focused team (Vaporize/Melt). It should also be noted that with many external Elemental Mastery buffs, such as (4) artifact set or Sucrose, Elemental Mastery slightly loses value.