You know who I'm surprised that isn't on this list and aren't used more in the tier?
Ninjask and Smeargle, both who used to be OU last generation.
Ninjask baton passing speed boost maybe gimmicky with all the phazers and hazers in this tier but if done correctly, can put the opponent on the back foot, as it works the same way as last generation.
Smeargle can do alot of things in this tier as also has access to spore, although it's main niche is probably baton passing belly drum, if you can pull off a belly drum pass to say something like ENTEI with extreme speed, i doubt anything without a focus sash, red card or Quagsire or have the Sturdy ability would survive, with usable speed and access to adamant extreme speed from a +6 pass from smeargle this tier will have a hard time countering it, since it can't be burnt and paralyze won't affect extreme speed unless your unlucky where 1 out of 4 chance that you can't move.
You could probably pass to other physical pokemon with priority like Shapreon, or pokemon just just fast in general like Sceptile.
Smeargle can also batonpass other things like shift gear, quiver dance and shell smash, although obviously venemoth and Gorebyss do this better, heck even dusknoir culd probably scare a few things with +6 shadow sneak.
Since those pokemon are likely to rise to UU because some pokemon are being banned to either BL or Uber (eg Kyurem and Garchomp) or some pokemon are moving down because of the lack of sunlight :P (eg Charizard, Victrebell). There's a good chance Venemoth and Gorebyss will move to UU. Leaving the job to Smeargle in RU, obviously Huntail would replace Gorebyss smash passing in RU.
