Now that people are finally going to evolve their starters, I looked at the moves in anticipation of people trying to rationalize their inevitably bad move rolls, and woof, they are going to be BAD.
(Note: I did the comparisons based on move DPS plus STAB if applicable. True DPS, which accounts for the base attack stat of the Pokemon will vary slightly. I also took snips from Silph Road for the moves, which can be misleading in a few ways. I don't think Charizard can actually get Dragon Breath and Blastoise doesn't have multiple Water Guns or Hyrdo Pumps it can possibly roll into)
Charizard is a nightmare, with two quick moves (three according to Silph Road, but I don't think that's actually the case), three charge moves, and one clearly superior set (Wing Attack/Fire Blast). Usually I would argue that it's better for your moves to match type and something like Ember isn't that much (if at all) worse than an off-type move like Wing Attack in practice, but Wing Attack is so much better (over 25%, which itself negates type advantage) and covers so many of the same types that there is no argument to be made, unless you really want to bring up steel or electric types as if they're actually relevant right now.
Blastoise is arguably worse, with its two non-Hydro Pump charge moves dealing only 50-60% of the damage of Hydro Pump. The gap between Bite and Water Gun is also the same as the difference between Wing Attack and Ember (though they have the same attack speed, so it doesn't suffer additionally due to dodge timings).
Venusaur is very forgiving on paper, with relatively minor DPS drops for sub-optimal moves, but in practice, can be just as bad. Razor Leaf's 1450ms animation time means you can only get one attack in between dodges, whereas the already superior Vine Whip can get three. That means in practice, Razor Leaf deals 15 damage per attack volley versus Vine Whip's 21, which equates to a much bigger difference (nearly 30%) than on paper (12.9 DPS vs. 13.5 DPS when spammed without dodging, or a 4.5% difference). On the plus side, if you lag or can only manage 2 Vine Whips between dodges, Razor Leaf is actually better (without factoring in energy generation, because shrugs). Also, while Sludge Bomb has the second highest DPS of Venusaur's three charge moves, it is a Poison move, which means it will usually deal 25% less damage than Petal Blizzard. That said, at least Petal Blizzard isn't quite the drop off from Solar Beam that the other starters' second/third best charge moves are.
Obviously, all of this only pertains to attacking, but the way the game's combat is currently balanced, I honestly don't think the efficacy of defensive moves is worth the discussion other than for discussion's sake. Then again, starters are mostly for aesthetics anyway, since there are pokemon that outperform them that are much easier to obtain, so really, maybe none of it was worth discussing. Oh well. It's going to be asked regardless.