http://tvtropes.org/pmwiki/pmwiki.php/Main/StopHavingFunGuys
That's what I mean. Pokémon is one of those games that has a TON of these people in them, and they are absolutely obsessed with these things. There's nothing wrong with catching any random mon and training it. It's when we get into discussions about "competitive play" that these guys come out of the woodwork and make me facestairs at every opportunity. It's a video game, it's for fun. Fun should not be massive grind coupled with algebra. If you find these things fun... It only takes a single job in the real world to figure out why these things are NOT fun. Especially when 8 hours of grind a day is what you do to make a living. Work =/= fun.
Charizard does take 25% resistance from Grass moves. But, let's suppose that Charizard is NOT level 100 for a moment. Let's also suppose that Charizard has below average Special Defense We'll just say he has a neutral nature. So, something around... what... 170-190 Sp.Def.? Maybe? If I remember right? Now, a Big Root doesn't increase damage done... But with STAB and Overgrow... it does alleviate that x4 resistance as well as do some decent damage if Torterra has a high Sp.Atk. (which mine does, along with a high Defense). Flying moves are nearly nullified by the simple High Defense of a Torterra. Fire moves also don't get the x2 bonus since Torterra is half ground. So, we have a Charizard who is doing normal damage to Torterra without a "It's Super Effective" message unless it uses a flying attack, and even then, most of those are nullified by the rather high defense of that starter.
So, Giga Drain with its 70 Base Attack multiplied by 1.5x due to STAB as well as the 1.5x for Overgrow. Turns the attack into a 140 base damage. Divided by 4, we're down to what... 35 base damage? Couple that with low HP and Low Sp.Def. of a Charizard and you can do a surprising amount of damage with an attack, especially with a critical hit. Does that mean my 90% is accurate? Gross estimation on my part. Attack that took a Charizard from nearly full health to fainted. Do I pretend to know how the mechanics of calculating damage work? No. I have no idea. I just know that while it may not be 90% damage, it's still fairly high, enough that a mon goes from green to fainted on its meter. I'd also like to mention that the Charizard was only 4 levels above my Torterra. Did I score a critical hit? No, I did not. But my two 1.5x together does take that x4 resistance down to x3 instead. Does having a low Sp.Def. on that Charizard help as well? Most likely. How about having a high Sp.Atk. on my Torterra? Yeah, probably. How much does it help? I have no idea in terms of raw numbers. I can only say that while it may not have been 90% of the health, it was enough that Charizard went from green to faint.
Also, that's something else that I've found irritating about the "Stop having fun guys" crowd. The change of "Lightning bruisers" to "sweepers". Did we really have to change the name for that? Seriously? I also never really see people with the "Sweepers", though a lot of guides recommend having at least one. Maybe that means I don't play online enough (which I likely don't, since nobody really plays for fun online and spends a lot of time EV training and breeding and blah blah blah) so I don't see all these "sweepers". Most of what I see is tanks, gimmicks, or pseudo-legendaries. Do I see glass cannons? Nope. I don't see many sweepers either.
But, that's just me. I don't mind playing and learning new things, I just don't like the guys who go massively out of their way to "be the very best, like no one ever was". Especially since a large number of these people are living off of my tax dollars. Anyway, that's neither here nor there.
I do love that pokemon is one of the most versatile systems out there for battle. I like that you can easily think of new ways to use common mons or find ways to make underused mons fairly powerful. I like that the moves are often fairly diverse enough that you can pretty much choose whatever you want on them. I also like that there is sometimes some fairly deep strategy elements to the series. What's even better is that these things only get better with time.
Maybe I'll just spend a ton of time becoming one of the "Stop Having Fun" guys in order to see the kind of mons you're talking about. Probably couldn't hurt any, at least. Well.... maybe I'll do that after I get to the second gym. It's really weird having 80 dex, 30 hours, level 30, and not even at the second gym yet.