The query could mean a few different things because "Episode 68" applies to several different series within the Pokémon franchise. Did you mean:
Please clarify which you are looking for so I can help you find where to watch it legally.
(The 68th episode of the original 1997 series) Project Mew! (Episode 68 of Pokémon Journeys) The Overlooker (Episode 68 of Pokémon Horizons)