Charizard in Smash represents the first generation and FR/LG. Just because a mega form exists for him, doesn't mean he will use it, and the complications of balancing him having a different final smash than Ivysaur or Squirtle wouldn't really work.
Lucario is "fine" moveset wise and already has a final smash (that isn't based on anything in Pokemon).
It's pretty evident from what we've seen that Sakurai doesn't make drastic changes to characters.lightly. We've already seen an entirely unchanged Sonic and Toon Link, the latter many people were confident wasn't even coming back.
I really doubt the Pokemon Company is some unrelenting force of pure marketing that this thread seems to believe. For Smash it isn't all marketing, and I'm sure if Sakurai isn't comfortable making every single Pokemon that appears in the game turn into a god as one of their moves, he doesn't have to.
Think about Pichu or Jigglypuff's final smash. If Pokemon company was really calling all the shots with a vice grip of marketing, why have Pichu as a joke clone character and Jigglypuff's final smash not based on anything from the game or cartoon. It's literally just making her bigger...
It's really weird. No other smash bros people were so quick to assume they'd drop everything for the new generation of Pokemon, and yet for some reason here we are with everyone that exists being mega and entire movesets reworked for marketing.