Gligar
Tier A
availablity: early-ish; requires windy weather
stats: average attack, good bulk
movepool: great naturally; insane if you breed for earthquake
Comments: very good typing; access to 2 incredible stab moves and a few other nice moves besides. Whenever Gliscor gets added he will be among the best pokemon in the game.
Tangela/Tangrowth
Tier A
availabilty: early-ish; low encounter rate though
stats: excellent physical bulk and good attacking stats
movepool: good status moves, good stab, and even a setup move.
Comments: while he's lackluster against special foes, he is a godsend against physical attackers. leech seed/sleep powder make him nearly unkillable while ancient power and giga drain give him decent coverage.
Charmander/Charmeleon/Charizard
Tier D:
availability: start of the game
stats: meh
movepool: meh, but decent hm slave
Comments: not bulky, no good attacking moves... cool pokemon, but he just doesn't do anything with the moves available.
You could breed him a couple of moves... but your time is better spent elsewhere.
swinub/piloswine/Mamoswine
Tier B
availability: late game; easy to get though
stats: meh
movepool: well above average
Comments: not very bulky, but hits like a truck.
Spiritomb
Tier C
availability: moderately late; difficult to obtain
stats: average
movepool: good
Comments: great typing, good stab moves nice setup move; unfortunately slow as hell, so you'll get hit by every opponent you find.
Porygon
Tier D
availability: early-ish; easy event
stats: poor
movepool exceptional
Comments: access most desireable tm moves, combined with insanely early psybeam make porygon an early game beast. sadly it quickly falls off due to its poor speed, poor typing, and poor stats. Upgrade comes pretty late; evolving it means no access to the much stronger link stone alternatives (and it'll still be pretty slow, with average stats).
trapinch/vibrava/flygon
Tier C
availabiliy: early-ish; somewhat costly slot machine prize
stats: meh
movepool: decent
Comments: lackluster offensive stats compared to other available pokes. great ability and great immunities.
tepig/pignite/emboar
Tier C
availability: start of game or deep into mid game
stats: solid
movepool: meh
Comments; if it learned a real fighting type move it would be... average...as it is it has nothing special about it rollout is fun, though kinda bad, aside from that it really doesn't have anything to recommend itself.
Kling/klang/klingklang
Tier D
availability: mid-game
stats: useable
movepool: shudder
Comments: it has no moves. discharge isn't great, gear grind is okay, but poor accuracy and a boring attack stat make it blah. Eventually it gets shift gears, which is amazing, but it learns stone nothing for other physical moves. For special moves it gets non-stab charge beam and nonstab discharge... It tries to be physical and special at the same time, but comes short for both. If you need a steel type, there are better options.
Cryogonal
Tier F
availabilty: late-game
stats: well... it's fast I guess...
movepool: it has one move and dual screens
Comments: do not use. dual screens are not useful; you will die to a single physical attack from virtually anything. It has decent special bulk, but lacks any kind of useful status moves. It can learn recover, but the existence of physical attacks more or less renders it useless
Gastrodon
Tier C
availability: mid-game
stats: decent bulk
movepool: lacking some things, but useable
Comments: it has a nice ability, nice bulk, but poor coverage and low utility
Pineco/Forretress
Tier D
availability: as soon as you get a pokemon with headbutt (as soon as the start of the game)
stats: great
movepool: broken
comments: hazards don't work currently, so forretress doesn't work well either. He can somewhat get by on bulk alone, but his lack of good moves will definitely make life hard. He gets bug bite which is decent, but other than that his only move is the lategame gyro ball. Aside from that he doesn't really offer anything. When hazards get implemented he will be nice (spikes and rapid spin are great), but until then he is not very good.