Snorlax and Porygon2 are certainly not necessary on all teams. Offensive teams can pretty much set up Rocks and other hazards and just force Chandelure out with faster mons to render it useless after 1 switch-in. There are plenty of offensive checks, too, such as your own Chandelure (one reason to go max Speed Chandelure), Arcanine, Houndoom, Flygon, Kingdra, Suicune, Rhyperior, etc. I can certainly find worse offenders of restrictions on teambuilding than Chandelure. Chandelure to me is analogous to Nidoqueen in RU for me; it packs a huge punch and is immediately threatening, but the metagame has sufficient amount of resources to handle said threat without overly limiting teambuilding options. Except, Nidoqueen in RU is far worse than Chandelure in UU.