1. Sabrina encounter
Sabrina is one of the characters that makes viewers feel the most `creepy` because of her strangeness.
In the two episodes `Abra and the Psychic Duel` and `Haunter vs. Kadabra`, Ash had a miserable encounter with Sabrina.
2. Spearow’s attack
Pikachu and Ash had a stormy first meeting.
Ash’s carelessness angered the Spearow pack.
3. Gary’s battle with Mewtwo
Ash has never directly faced Team Rocket’s boss, Giovanni, in a 1-on-1 battle. However, his main rival, Gary Oak, has had the opportunity to encounter Giovanni.
Indeed, this was a very scary match for Gary.
4. The Tree of Origin and Lucario’s sacrifice
In the movie Pokémon: Lucario and the Mystery of Mew, Ash and his teammates encountered a Lucario protecting its kingdom.
The Tree of Origin is not only guarded by the legendary Pokémon group Regi, but also has a fearsome protection system.
Eliana 
Xavier 
Grayson