Kanto - Aerodactyl and Kangaskhan (a tie)
Johto - Lugia
Hoenn - Spoink (2nd place would be Mudkip)
Sinnoh - Chimchar and it's evolutions.
Unova - Volcarona
Did you ever find that fabled lv 100 magikarp in Platinum?
I didn't catch it, but I spent about 3 days trying to hatch an Adamant Timburr. Catching wise was Mewtwo in FR/LG, I spent about a day trying to capture it.
What is your least favorite Pokemon from each generation?
If I remember correctly, I think my first powerhouse Pokemon was Rayquaza from Pokemon Emerald. I did beat the Elite 4 with other Pokemon before, but I don't remember them ever sweeping a team.
Speaking of legendary Pokemon, what was the first legendary Pokemon you ever caught in a Pokemon game and what version was that Pokemon in?