Squirtle actually does have a problem, Olimar will Grab you and throw you off the edge, and when you are recovering, he will use F-smash to Send his Pikmin to Gimp your Recovery. This hurts sqiurtle a bit, but not soo much. Charizard >>>>>> Olimar i swear, i was just playing a godly olimar and I Rapped his Olimar really hard. One rock Smash and a F-throw and Olimar was Dead, because i happened to kill every single PIkmin with the Rock Smash.
I'm going to aknowledge that fact that you don't know what you're talking about, or you're playing an Olimar who has just located the Z button. *cough* Or extremely good *cough* I think I can disprove this for you first hand.
My opinion
Olimar v Squirtle: 55/45
Right off the bat we can eliminate Squirtle's ground game because of Olimar's near impervous grab game, that leaves Squirtle to shift through it's aerial options. You guys have a point that Squirtle can shake off Pikmin using his Nair, but any Olimar can tell you spending time destroying Pikmin is going to get you punished or killed. Squirtles got Bair and Dair, which don't seem all that tough to beat. I'm taking a guess at this, but because Olimar's Uair isn't attached to his body, I'm pretty sure it can go through Squirtle's Dair, Bair for sure. Squirtle has two jumps like most normal characters which means ledgeguarding isn't going to come too easily for him. He's got one,maybe two chances to hit Olimar with Bair before he has to retreat for the ledge himself and let's face it, Squirtles recovery isn't too great. The reason I say 55/45 is because if Squirtle does manage to get Olimar off the ground, the match can become very difficult because of Squirtle's speed. It will allow him to keep the pressure on Olimar and increase the probability of mistakes from even the best Olimars.
Olimar v Ivysaur: 60/40
If an Olimar is able to camp then he'll probably do it. Ivysaur's Razor Leaf cuts Pikmin in half, but Pikmin spam is much faster and have you looked at their damage? Ivysaur will go from 0% to 70%+ in a little under ten seconds if he doesn't remove the Pikmin. Ivysaur has to approach if she wants to have any chance to win and because of that she puts herself at risk. Overall, there aren't too many safe options for Ivysaur, but she can't be counted out. If Bullet Seed can land a hit, then Olimar's damage is going up making it vulnerable to Charizard. Bair and it's other offensive options can prove trouble for Olimar, but other than that there doesn't seem like much it can do.
Olimar v Charizard: 50/50
From what I learned about PT, thus far, Charizard should not be out until later on. The argument that Olimar is going to skyrocket his damage then KO him in such an effortless manner as a F/Usmash is wrong. When Charizard does come out, it'll be only vunerable to shorter combos like D/Uthrow into Uair, but that's about it. Charizard's Flamethrower can be angled and when used defensively it can stop Olimar from approaching and give Charizard a moment to calculate it's own counter measure. Rocksmash is going to decimate Pikmin, though they can always be plucked again, and deals tremendous damage. Off edge, Charizard can easily gimp Olimar because of his triple jump and aerials. Yes, Olimar has the Whistle, but with three jumps Olimar can hang out before having to grab the ledge again. Because of his power, combos like jab-jab-grab can easily put Olimar into the KO percentages, which makes it a bit difficult to hold an offensive against charizard. Despite all of this, we have to look at Charizard's dimensions and realize he's a really big target. Even though he's got a lot going for him against Olimar, there is still Pikmin spam, an impressive grab, faster aerials, and plenty of KO options for Olimar.