Good partners for Saberlot?

Okita would be a great pick for him for her stargen. So you could have for the crits team Lancelot/Okita/Waver, waver could be switched out for Tamamo or such since Lancelot works good in a arts team as well as.

Saberlot is an Arts/Crit servant, so his best allies are those who can buff his crits, can generate stars, or buff his arts performance.

Waver, being a universal support, is great on Saberlot due to the crit buff and a triple arts deck. Tamamo can also be a good support for the arts buffs and cooldown NP due to Saberlot's arguably long skill cooldowns.

Hans can provide additional stars, durability and can also boost crit damage, while Jack and Fuuma are premier star generators that can help Saberlot crit.

I think:
1. Waver. Self explanatory
2. Tamamo. Self explanatory
3. Nero Bride (full support mode instead damage dealer)
Party: Lancelot, Tamamo, Bride/Waver.
Lancelot equipped with Formal Craft or Another Ending and support equipped with 2030 or His Rightful Place for steady stars supply.
Alternatives: Hans, Helena, Caster Gilgamesh (when he's released).
I think you shouldn't use servant like Okita because deck matters, you need more Arts and not Quick for Lancelot.