How do you get Ho-oh in Pokemon Stadium 2?

You can't get Ho-Oh in Pokemon Stadium 2.

Ho-Oh is a legendary Pokemon that is not available in the game. You can only encounter and catch it in the main Pokemon games, like Pokemon Gold and Silver.

However, you can battle against a trainer who uses Ho-Oh in Pokemon Stadium 2. This trainer is found in the "Challenge Mode", specifically in the "Master Cup". Be prepared for a tough battle!