Ho-oh in the sun.

solarbeam for groudon

I read this title like the song Blister in the Sun

well Solar Beam and Fire Blast both get the 20% bonus for clear as they are grass/fire. And they do almost identical damage in a neutral matchup, tiny bit more for Fire Blast. So it comes down to who will you most often use him against? Both neutral against normal, so Blissey/Snorlax doesn't factor in. Fire kills all the grass and bugs, Grass takes out ground, rock and water. So because you are more likely to see Rhydon, Vape, T-Tar in gyms than Eggy or Venusaur or bugs, I'd probably go Solar Beam. But either way Ho-Oh is a lot better than you think, does a huge amount of total damage, will be a very potion efficient generalist. Does 50% more damage than even TTar or Dragonite

Great question. No precise answer other than: it depends. I also am in Arizona, and I would have to quibble with you about the "clear over 90% of the time." I think it is more like 89%, but, then again, if there is even a wisp of a cloud on the distant horizon, that makes it "partly cloudy" by Arizona standards.

So what does it depend on? Many things. One of which is the other pokemons in your portfolio. I have a great Entei, actually two, one with Flamethrower and one with Overheat. So I am more in need of a great grass attacker, and therefore I am going with Solar Beam on my first Ho-Oh to power up. Not sure yet on the second Ho-Oh. Right now I think I want to power up one with each charge move, but my order is probably grass, flying and then fire, but only because I have other really good fire attackers.