Tyranitar
- Slightly higher Attack than Rhydon
- Faster and only a little defensively weaker than Rhydon
- Learns moves like Stone Edge, Earthquake, Crunch, and Strength
- Found in the Safari Zone
- Has 6 different weaknesses
- Evolves very, very late
Rhydon
- Base 130 Attack is only a little worse than Tyranitar
- Better HP and Defense than Tyranitar
- Learns moves like Stone Edge, Earthquake, Hammer Arm, and Megahorn
- Found in the Safari Zone
- Rhyhorn evolves late, but not as late as Pupitar
- Same amount of weaknesses as Tyranitar, but has two 4x instead of just one
It would seem that Tyranitar is the better choice. However, Pupitar evolves at Level 55, and due to Johto's level curve, you're practically guaranteed to not have a Tyranitar before entering the Hall of Fame. This means you actually need to compare Rhydon to Pupitar for the Johto segment of the game (Kanto is a different matter).
Pupitar has much worse stats in everything except Special Defense and Speed, so it's wholly offensively outclassed by Rhydon. It also doesn't get nearly as many good moves as Tyranitar, and another 4x weakness. This means that for beating the Indigo League, Rhydon is a much better choice than Pupitar. Here's a set:
Rhydon @ Muscle Band
Ability: Rock Head
- Earthquake / Dig
- Stone Edge / Rock Slide
- Hammer Arm
- Strength
However, in the long run, Tyranitar is better for beating Red. It has a better matchup against his Pokemon, and is just a generally stronger Pokemon. If you're planning on playing through Kanto and defeating Red, then I recommend using a Tyranitar instead of Rhydon, with something along the lines of this:
Tyranitar @ Muscle Band
Ability: Sand Stream
- Earthquake
- Stone Edge
- Crunch
- Thunder Punch / Avalanche
Good luck! :)
