As a suggestion for the guide itself, maybe you could list off when the Pokemon are going to come in most handy(for example Ninetales for Serra's gym).
As for a Pokemon...
Magnezone
Tier: B
Availability: Mid-game
Stats: Very good
Movepool: Rather poor
Alright, from that movepool rating I gave, you might be turned off Magnezone... don't let that deceive you. A solid base special attack stat of 130 makes it a very hard hitter, which is greatly supported by its typing that allows it to resist some of the most frustrating moves in the game(Serra's ice types, for example). Very few Pokemon carry Earthquake as of now, which means you don't need to worry about getting hit with a 4X weakness. Defensive stats of 70/115/90 make it a solid bulky attacker. If you need to combat annoying water types, Serra's ice types, or want to resist a handful of moves that will be thrown at you, go with Magnezone.