The thing is, "which Pokemon is better" is really a relative thing. Thunderus might be considered "better", but once it's kicked off to Uber Tornadus becomes a formidable foe in OU that can Rock You Like a Specs Hurricane
. Aggron is a bajillion times better than Aron, isn't it? Well slap a FEAR strategy on Aron
and see it do what the green-eyed Iron Armor Pokemon can't. The list goes on and on - a quick search on YouTube reveals sweeps of all kinds and people beating Ubers with much lower tier Pokemon.
Every Pokemon is usable in its own way, just where and how it's used.
A little tidbit to know after reading that long rant: Yay for my 100th post!