Pokemon I hated in Hoenn:
Norman's Slaking - Hits like a tank... literally does.
Pelipper - Those birds and their Protect strategy... they try to eat my PP!
Trapinch - Darn Arena Trap!
Liza's Lunatone/Tate's Solrock - The two you never want to see together... they annoy you with the Calm Mind strategy.
Spinda - I hate how most of their moves rely on confusion.