WOW. Where to start. Well, for me, "Daddy" is the hardest, Slaking with that Yawn and high defense... *shivers* But all of them had their own strengths, and the difficulty is really based on who you have on your team. Even with Treecko Roxanne's Nosepass was hard. Then Wattson the Magnemite/Magneton's typing made it difficult since I didn't have anyone strong for fighting against him. Tate and Liza were actually easy, seeing I'd carry a Mightyena and Sceptile for a Bite/Leaf Blade combo.