Ninjask is considered the ULTIMATE Speed Baton Passer.
With access to Speed Boost, protect and Subsitute, it can almost 100% pass over Full speed.
Smeargle is definitely one.
With legal access to Belly Drum, Subsitute and Spore, it can pass over a full attack boost.
Blaziken is EPIC with Speed Boost, Swords Dance and Substitute.
It can be the same as Ninjask with S-Dance and Speed Boost.
Eveelutions are good Calm Mind Passers.
With Umbreon for Bulk, and HP, it can pull of C-mind and Jolteon same with the speed
I will add more later.
This has the best Baton Passers in the Competitive Grounds from Smogon itself.