Any episode with Tutwig in it is a good episode to me!
Team Rocket's antics in the Sinnoh Underground were way more appealing to me than Ash's Gym battle with Gardenia tbh; I especially liked how TR's eyes turned into Spheres. Anyway, Gardenia's Cherubi must've been pretty durable to force Ash to switch Pokemon and I screamed when Staravia lost to Turtwig. Turtwig vs. Turtwig was enjoyable though.
I liked how, just like in the games, the writers put in the Sinno Underground.
Claimed by me!