In Genshin Impact, a free-to-play mobile and console game, the best way to get the most out of a character is to build a team around them that best utilizes their best traits and abilities. Because it is a game that steers players towards spending money to acquire better characters it's safe to assume and understand that the best teams are comprised of premium content characters. However, there are many viable alternatives, especially for Xiangling since most of her ideal teammates are available on regular banners, as is Xiangling herself.
Xiangling is a DPS character that focuses on Pyro elemental attacks but can be quite flexible in dealing out physical damage as well. She is versatile and thus her team must be able to support her when she delivers both elemental and physical combos to take out her enemies. The following team is comprised of members that can do just that for her in the heat of battle.
6 Venti
Venti may be the second-best choice when it comes to supporting Xiangling and playing that role on her team, but that doesn't mean he isn't without his merits. His whole point when looking at team composition is to gather the enemies in groups so his DPS teammates can take them out in an efficient manner.
When comparing him to someone like Sucrose, who we'll cover later, his big fault is that the enemies are sent airborne which isn't ideal for someone like Xiangling whose attacks plant her with her feet on the ground. That's the one issue you'll have to learn to work around if Venti ends up being your only choice in terms of a supporting character. However, since he's the only limited-run five-star on this list you'll be unlikely to have this problem.
5 Diona
Diona is an interesting choice for Xiangling's team as she can both heal and deal Cryo Elemental damage. The former ability is self-explanatory, but the latter allows a Pyro Elemental user like Xiangling to deal Melt damage, which is possible when an enemy has already been hit by a freezing attack that dishes out Cryo damage.
Diona can also shield allies and the strength of this shield scales based on her health points. She also happens to be a ranged character that uses a bow, which is ideal for support characters that can also heal if need be.
4 Xingqiu
Anyone who is looking to boost their damage output should consider the addition of Xingqui to their team roster. He is a sword-wielder that is listed as a support and DPS character, and his abilities are rather electric, despite his damage element being Hydro and water-based.
Xingqui's Elemental Burst skyrockets Xiangling's damage output and makes it so abilities can be cast quicker at much faster intervals. It's a rather impressive feat to be able to buff your allies while at the same time being a capable damage dealer in your own right. Xingqiu's flexibility in battle makes him useful in more than a handful of scenarios you may come across while playing Genshin Impact.
3 Sucrose
It's rather comedic that Sucrose has the name that she does, despite being one of the best support characters in the entirety of Genshin Impact regardless of classification or reason. Her skill set focuses on Ameno Elemental use, which relies on the wind. She can suck together enemies, making them easier to dispatch as they can be gathered relatively close to one another.
In addition to gathering enemies in this manner, she can also buff allies and debuff the enemy. Combining her with both Xiangling and the other two characters ahead in this list, it will become quite clear how useful and appreciated her ability to make the elimination of enemy groups much easier.
2 Rosaria
Genshin Impact does a good job at making certain Elemental attacks work together in a way that is logical and rewarding. Rosaria at first glance may seem like an odd choice for Xiangling's team as she does Cryo damage, but it benefits the team.
Spreading the freezing element will allow Xiangling to dish out Melt DMG which happens when a frozen enemy is then hit with Pyro-focused attacks. In a way, Rosaria functions as key support as she sets up the bowling pins and Xiangling comes in and knocks them down. A character like Rosaria that can be both a DPS character and support, arguable making her a must to be on almost any character's roster.
1 Bennett
Healers are an important part of any strong or sustainable team and Bennett serves that role brilliantly while also being steady support, as well. His Elemental Burst heals the team while at the same time providing those around him with an Attack DMG buff.
This buff scales solely based on Bennett's Base Attack which is comprised of his level plus weapon damage. It doesn't hurt that he shares the same Pyro Elemental type as Xiangling, making them rather synergistic with one another. Bennett serves two roles at once and quickly establishes himself as an irreplaceable and invaluable team member.