To be honest, Pidgeot hasn't proved her strength yet. The Only battle it has is with Fearow! But as a Pidgeotto it was awesome, although it wasn't used in battles that much when bulbasaur, charmander and squirtle came. Poor pidgeotto! Stupid Ash for not fulfilling his promised to this Bird!!
As for Staravia, i mean STARPTOR!!, now that it evolved! Im very sure it'l become Ash's Powerhouse in Sinnoh... Although i would say that almost all of his current team are strong.. STARPOR will sure to shine. I just noticed, Ash's Starptor is not that big as Pidgeot and the Staraptor shown in the rioulo episode.
Swellow for sure is strong! its Electricity resistance made this one cool! and it'd proved it self having a numerous wins in Hoenn Region... So i'd say this Bird Rocks! the only thing that differs this to ash's other bird is that it's charm is not that attractive, making it the less fame among kids.
Id stick to my first Post. Noctowl is the weakest. It might a phychic type pokemon and a shiny one. but it didnt shine during Johto. It might defeat gengar! but thats it. Its didnt contribute much in Ash's Johto team. Well I would say aswell that Ash's Johto Team is his weakest TEAM of All. maybe because most his pokemon didnt evolve. Only Chikorita made it to evolved to Bayleaf! Remeber that in the silver conference Ash needed to call for her kanto pokemon the achieve his spot there! Thanks to charizard!