A* - Ponyta, Abra, Porygon, and Timburr
Ponyta is the only one here which needs elucidation so, I'll elaborate my thoughts. Ponyta is a great defensive Pokemon which has access to Recovery, and Will-O-Wisp, whilst remaining in the 19 speed tier. This allows it to out speed and burn, Mienfoo, Pawniard, and to a lesser extent Drilbur, Archen, and Tirtouga. Its ability also allows it to spread burns effectively such as coming in on a resisted attack, namely U-turn. It can also run an effective Sunny Beam set in conjunction with Vulpix.
A+ Archen, Spritzee, Fletchling, Chinchou,and Magnemite
Spritzee is the only one that really needs explaining here. Spritzee is a great bulky Pokemon, whom I love to use on stall team. Spritzee uses one set, okay, that is a problem, but who cares when that set walls everything to hell, and spreads wishes and aromatherapy around. This is more of a personal changes as, I love stall teams, and Spritzee provides health to Pokemon such as Ferroseed, Chinchou, and many other Bulk Pokemon that are in LC without reliable recovery.
A Croagunk, Ferroseed, Snubbull, Staryu, Tirtouga, Gastly, Vulpix, Vullaby, Omanyte, Drilbur, and Diglett
Ferroseed is a great bulky Pokemon but it relies way too much on other Pokemon for healing whether it be by Wish, or Leech Seed for me to get it A+. Vullaby is one of the best Bulky Pivots, and Defog access is nice, whilst Brave Bird hits hard. Diglett is the better trapper between it, and Gothita. FletchDig is a great core still, and emphasizes that Diglett traps, Ponyta, Magnemite, Chinchou, Vulpix, Omanyte, Croagunk, and Houndour, while Gothita does not trap nearly as many Pokemon effectively.
A- Carvanha, Cottonee, Foongus, Gothita, Houndour, Pancham, Pumpkaboo-Super, Shellder, Skrelp, Stunky
Foongus is a lord, yes, but Foongus' Spore is not as much appreciated as it once was, and then Foongus can be Set Up fodder, whether it be Fletchling, or anything else for that matter. Houndour is the second best Pursuit trapper next to Pawniard, it has great STABs and utility in Sucker Punch, Pursuit, Fire Blast, and its only downfall is pretty drastic, but can be overcome with teambuilding, this is a weakness to Fighting. Rowan epitomizes why Pancham deserved to drop down. Stunky is a great offensive Defogger, is in the 18 speed tier, and counters Abra whilst trapping it. Very underrated Pokemon that I think deserves more recognition.