I don't know what to choose for fourth move for my ho-oh.
I got this move set now:
for fourth move i'm thinking about calm mind sunny day or thunder wave.
Thanks in advance :)
For the fourth move, you could try Brave Bird or Sky Attack. Both have good power and are STAB for Ho-Oh, and give coverage against those tanky Grass and Fighting types.
Iron HEad as it covers Rock Types, Ho-Oh's main pests.