Why's this episode so underrated? I just remember it briefly as a kid, but now that I rewatched it I easily have it in my top 10, maybe even 5. Not only does this give Sceptile a much-needed character development and arc to go through, but it also shows just how strong his bond with Ash is, even though he never had to rely on anything like a special training, special ability, tragic backstory, one-of-a-kind ability, or anything like that through his battles, no, Sceptile is Ash's first ace that he has started training by himself, just the two of them, and the growth that they had through it is evident in just how much Sceptile developed from a stubborn Treecko that was constantly picking himself back up from losses to a more competent Grovyle that still had ways to go, and then finally into a mature Sceptile that even then had a rough start, but was shown to have immense potential anyway.
The theme song that plays as Sceptile and Ash weakly walk helping each other and picking each other on the way to finding Pikachu, connecting with each other, and showing just how similar they are was absolutely beautiful to see. Even when unable of using any moves, he still was brave enough to put himself in the middle of Ash and hundreds of angry Beedrills, he still had the willpower to go through so many things all because his heart was broken by something that didn't quite go right, and this is what in my opinion makes Sceptile so interesting as an ace because aces usually have a resolution to their biggest arc through a shining battle against an important rival that has had a deep connection to them while being tutored by Ash and connecting deeper with him, but here Sceptile's resolution had less to do with fighting, and more with coping with being unable of fighting and how we all feel weak sometimes, with Ash being the primary resolution here rather than a factor used to achieve such resolution solely.
Overall, 10/10 episode IMO. I loved every single moment of it. The whole thing about Pokemon and humans connecting with each other, as Ash constantly sacrifices himself to avoid further harm to Sceptile, and Sceptile grows to respect Ash more and more with each step they give, this was all just so damn beautiful to watch. Also helps that Spenser is a very charismatic character that was willing to help them through it, and with how Sceptile has a battle for himself to shine in after being cast aside so much throughout the Battle Frontier up to that point, this all just felt like solidifying Sceptile as Ash's first ace that he trained solely by himself and building the grounds for what would later be the first Pokemon to beat the Legendary Darkrai that swept right through an entire region.