Okay, guys, I'm feeling generous. Red Ryu, you're probably going to **** me over with this at next tourney. lol.
As far as Squirtle goes, you need to CAMP, CAMP, CAMP, especially boms can be a huge hinderance. Also, abuse the crap out of your disjointed hitboxes, because though Squirtle's aerials may be fantastic, their range is not that great. You have to space really well, and make sure you're on your toes against Squirtle's ridiculous mobility. Do not EVER stop spamming your projectiles, because myself and other PTs (I'm not sure how much other people do this....) love Hydroplane moves, and I will be on the complete opposite side of FD one second, and the next you'll find yourself either in the air from a U-smash, going off the stage from a D-smash (in which case you will be f-air'd and Water-gun'd to death), or grabbed, and thrown off the stage, in which case you are again screwed by being off-stage. Do keep in mind that your recovery will beat Squirtle's aerials, though, so there is hope. lol.
With Ivysaur, I dunno. Just win. He kinda sucks. Ryu is right in saying that yeah, Ivy's b-air does space pretty well, but as long as you keep up the camping, Ivysaur is helpless because all he can do is bait approaches with Razor Leaf, which gets killed by Link's everything. X_X
As far as Charizard goes, keep him at mid-long range. The longer the better, but you really have to mindgame Zard because he outranges Link in most moves if I'm not mistaken, so just make sure you keep spamming to shut down his approach. Watch out for flamethrower, because Link's weight will make it significantly more difficult to get out. And again, be really careful about getting gimped. Between Charizard's grab range, ground speed, multiple jumps, and ridiculous knockback on the sweet parts of his F-air, you can find yourself in a situation where you'll be pulling your hair out because you keep missing the ledge from Charizard aerially beating the crap out of you.
I hope this helps?
In summary, I'd say this:
60:40 Squirtle
35:65 Link
55:45 Charizard
So overall.... 55:45 PT I'd say. I wouldn't go as far as to say 60:40 unless you play the matchup poorly.