Heatmor @ Leppa Berry
Ability: Flash Fire
EVs: 252 HP / 252 Def
31/00/31/xx/xx/xx
Bold Nature
- Lick
- Fling
- Recycle
- Rest
That thing would allow you to drag that battle out for all eternity. Flash Fire means that Sunny Day, Sacred Fire and Fire Blast are all irrelevant. Lick is to paralyze Ho-oh without dealing too much damage. Leppa Berry + Recycle + Fling means that neither of you will run out of PP. Rest to heal if the damage from Ho-oh's Punishment starts to add up. EVs + IVs + nature so you deal as little damage as possible, while taking as little damage as possible from Punishment. Add something with Heal Pulse, if you are really REALLY paranoid about killing it with your ~30th Fling...