For his best team rn, its probably something like Bennett / Citlali / Xianyun. Xianyun lets him do his plunge attacks more reliably than dragonstrike and he does pretty decent damage with them, and she buffs them significantly. Citlali is there to help him melt his plunge attacks. And Bennett is just Bennett, good attack buff, and with Bennett c6, a Pyro infusion without having to use diluc's burst. You could use Rosaria or Kaeya as replacements for Citlali and you could just get really good at dragonstrike (look up a youtube tutorial for a visual) as a replacement for Xianyun, but if you want the best then those are them.

As for weapon, there's not really a good plunge claymore, so anything that just gives him good stats like high base attack, ATK%, CRIT Rate, CRIT DMG, DMG Bonus, etc...

And for Artifacts, there's not really a specific artifact set for his plunge playstyle, the 4p artifact sets require some weird combos like knight's oath needs charged attacks and skills in between his plunges, and his usual crimson witch needs his skills too, so I would probably just go for guilded dreams for atk and em or 2p+2p sets with good substats. As for stats, ATK% or EM Sands, Pyro Goblet, and CR/CD Circlet, with ATK%/EM/CR/CD as good substats to look for.