Dragonite's Advantages:
* Stronger Stats: Dragonite has significantly higher base stats across the board, including higher Attack, Special Attack, Speed, and Defense, making it much more durable and powerful in battles.
* Stronger Type: Dragonite's Dragon/Flying typing gives it a significant advantage over many common Pokemon types, especially with its access to powerful Dragon-type moves like Outrage and Dragon Claw.
* Better Movepool: Dragonite has a far wider and more powerful movepool, including access to powerful moves like Earthquake, Thunder, and Hurricane.
* Higher Level: Dragonite evolves at level 55, meaning it will generally be much higher level than Pidgeot when you obtain it, allowing it to learn more moves and have higher stats.
Pidgeot's Advantages:
* Early Game Availability: Pidgeot is available much earlier in the game, making it a solid option for the early stages of the game.
* Good Speed: Pidgeot has high Speed, making it a fast attacker.
Overall:
While Pidgeot can be a useful early game Pokemon, Dragonite's overwhelming advantages in terms of stats, typing, movepool, and level make it a far superior Pokemon overall in Pokemon SoulSilver. Dragonite can be a powerhouse on your team and will easily carry you through most of the game.
Conclusion:
Dragonite is the clear winner in this matchup. If you want a strong and versatile Pokemon, Dragonite is the way to go in Pokemon SoulSilver.