Though this is clearly no excuse to use a Charizard, is there any special attack in the game more powerful than sun boosted solar power Blast Burn from specs Charizard? I did some calcs with other powerful moves in Ubers, and I was surprised. I used Blissey as an arbitrary punching bag. Also, the Honkalculator doesn't have Blast Burn, so I used full health Eruption instead, as they have the same power.
252+ SpA Choice Specs Solar Power Charizard Eruption (Blast Burn) vs. 4 HP / 252+ SpD Blissey in sun: 466-550 (71.47 - 84.35%)
52+ SpA Choice Specs Kyogre Water Spout vs. 4 HP / 252+ SpD Blissey in rain: 393-463 (60.27 - 71.01%)
252+ SpA Choice Specs Reshiram Blue Flare vs. 4 HP / 252+ SpD Blissey in sun: 340-402 (52.14 - 61.65%)
252+ SpA Choice Specs Deoxys-A Psycho Boost vs. 4 HP / 252+ SpD Blissey: 280-331 (42.94 - 50.76%)
252+ SpA Choice Specs Kyurem-W Draco Meteor vs. 4 HP / 252+ SpD Blissey: 268-316 (41.1 - 48.46%)
This isn't meant to encourage the use of Charizard, but it may explain why people use it perhaps.