In Pokémon Silver, I tried to catch Ho-oh once. I had spent my Master Ball on Lugia already, so it wasn't that easy. After a very long time of stupid moments, it Struggled itself to death. So I turned off my device and continued to where I didn't start catching it yet. I decided to try it again later.
When my starter (a Feraligatr named Kroko) got to level 70, I wanted to try it again. I got through the whole tower and attacked Ho-oh.
Kroko used Surf. Ho-oh had ½ of its HP left.
Kroko used Cut twice. Ho-oh's HP was in red.
I threw an Ultra Ball. Caught first try.