Aside of assassins I want some options for team members with Quetz as DPS (Against powerful caster enemies).
Enkidu and Dantes can make the work but they refused my summon.
Kintoki Rider is a very good welfare star generator, and his event is having a rerun in a few months if you don't already have him. Emiya is also decent on generating stars in his NP. Mozart's third skill generates 30-50 crit stars on demand, and being a 1-star, requires very little material to upgrade.
Hans can generate 9 stars/turn for 3 turns with his 3rd skill maxed (and up to +40% crit dmg with his 1st skill maxed), and Merlin generates 5/OC level for 5 turns with his NP
Saber Lancelot can generate 15 stars for three turns and another 20 stars on demand simply by being there and using his skills.
The best is always Merlin and Hans, or any 2030 supportive casters including Waver Helena, etc. Also 2030 Nightingale.
If you want to utilize Quetzalcoatl's natural of high star weight from riders class, rather than her 3rd skill, then any non-assassin servants with star weight higher than Casters are not quite recommended. Although rider's star weight of 200 is high, but in many cases, lancers, sabers, etc still will steal many stars then reduce chance of critical damage for both servants.
If you want to utilize her 3rd skill to kill enemy in 1 turn, then Mozart, or supportive servants with Golden Captures the Carp (with combat suit as mystic code), or some servants with NP of 1 turn star gain (like Drake). However, I can understand you needing for a more constant star generator. Therefore 2030 casters or Nightingale are best to pair.
Herself can also bring a +3/+4 star CE with other offensive buff. Thus far, like free MLB Maiden Leading Chaldea, Hot Spring Under the Moon, or not welfare Glory Is With Me, etc.
If you want to enhance your team's attacking power particularly facing multi class enemy but still posses critical star for Quetzalcoatl, Cu Alter and Raikou are good pair. Raikou won't steal any star if you dont operate her 1st skill, and Cu Alter will send star to your Quetzalcoatl. MHXA in the future could be another option, with even better star generator. But again if only considering send star to Quetzalcoatl, imo, 2030 Casters/Nightingale> Berserker >= Dante > 2030 umu Bride > servants in other classes.
