But I'm going to have to disagree on top tier.
I think he was arguing for Mid Tier, not High. Arguing Cubchoo for High Tier is a little bit absurd, given its terrible defensive typing, speed, and general lameness before evolving.
And requiring TMs to create a lacklustre coverage just seems like an over-accommodation.
TMs are reusable, so this point is flatly wrong. Having a good TM learnset is an amazing bonus for a Pokemon. And Beartic can learn several of the most important coverage TMs - Brick Break, Aerial Ace, Shadow Claw, and Rock Slide. Add relearning Superpower and you have a great Pokemon coverage-wise.
That being said, I'd still argue for Low or Lower Mid (if the tier is created), since Cubchoo is too late in the game, dead weight until he evolves, hard to find except in Winter, slow, and too weak against attacks that become fairly common late game.
I'd also like to say that Snivy is absolutely awful. For a starter, it is outclassed by loads of other grass types,
Not really. Snivy is the only Grass-type that fills his particular niche, so he can't really be outclassed unless you stretch the term pretty far. And while there's no huge demand for fast, bulky Grass types, if you want one he's pretty much the only option.
it is outclassed by tepig/ oshawott,
So what? Just because the other two starters are generally better shouldn't have to much of an effect on Snivy's tiering. While there is the opportunity cost of not getting either of the other two starters, it's still a Pokemon that is quite literally handed to you at the very beginning of the game, so if he's at least tolerable he shouldn't be Bottom tier.
And besides, it's not like Snivy is necessarily "outclassed" by the other two, since it gets the best boosting moves and has the best survivability against foes that can't hit his weaknesses.
it has an awful movepool without resorting to TMs. With resorting to TMs it becomes bearable.
Why shouldn't we consider TMs? I'll concede that he's severely lacking in coverage options, but I'm hesitant to say his movepool is awful, since he gets pretty good STABs at good times, Growth, and eventually Coil.
Early game it suffers to the 1st (the monkeys are better)
Would you really use Tepig or Oshawott against this fight, though? And besides, using Snivy has the advantage of pitting you against the absolute easiest Monkey, while you've just picked up the absolute best one.
3rd (this was a huge struggle) gyms.
Oshawott doesn't fair too much better, what with all the Sewaddle running around.
Late game it just sucks. It's only real saving points would be the fast leveling and the 5th gym, even then some of the ground types can give it difficulty.
Coil with his bulk and speed buys him a fair amount of time to set up and sweep. Even if you are forced to use a neutral Return, you'll still hit OHKOs pretty often at +3 or more Attack.
Bottom tier even when not compared to the other options available.
I'd say Mid Tier, maybe Lower Mid if the tier existed.
Edit: just looked up meganarium and Serperior is worse than even that...
Serperior has 34 points of Speed over Meganium, Growth, Coil, physical attacks, and Leech Seed. They're hardly comparable.
Mid tier is too generous for such a limited poke.
He's easily accessable, gains good STABs at good times, has good bulk and great speed, and so forth. He's not amazing, but he certainly isn't Munna bad.
Also, it's worth noting that Panpour is mostly a faster, frailer Oshawott that hits its final evolution 14 levels sooner and has a slightly different movepool (Acrobatics instead of Megahorn, Brick Break instead of Revenge, etc.). So you don't really lose that much by picking Snivy over Oshawott.
Tepig's evolutions have the unfortunate property of being Fire/Fighting Pokemon without being either Darumaka or Scrafty/Sawk, and Pansage suffers from not being Petilil, so it's entirely reasonable to avoid Tepig on grounds of being redundant.
So it actually isn't unreasonable to suggest Snivy simply for the free Panpour, which is admittedly a weird and counter-intuitive choice, but still perfectly valid. Since none of the three starters are really amazing compared to stuff you can find in the wild in this game (Oshawott being a partial exception, being somewhat better than anything else you can find), it ultimately doesn't matter too much what starter you pick.