You basically answered your own question. G&W has a hard time dealing with Squirtle's speed, and juggling him is not too hard, so that's Squirtle's job. Space with Ivy, projectile camping isn't too hard since razor leaf is so good and the bucket reflect isn't scary at all. With Ivy it's important to play safe. Don't play risky, that's where G&W will consistently punish with an up b and you'll take a lot of damage. Don't just rush in on bombs, just hit them and wait for the right moment. All of G&W aerials have a lot of lag, so if he lands with dair/bair/nair just make sure to shield all the hits and get the right punish. When G&W gets too aggressive with these landing options you can get easy grabs with Ivy which obviously can lead to lots of damage and early kill confirms with down throw up b and down throw nair up b etc. Ivy and Zard both can outrange G&W. If you go offstage, only go for deep ivy nairs or else you will be in danger of up b gimps. It might be better to just camp at the ledge and wait for sh dairs instead, which might be hard to land on G&W but lacks any risk and can be very rewarding. Other than that just go for the ledge trap. Don't be overly aggressive or he will land down smash and you will die at 60%. Rather, outrange him so that option is not viable (i.e. ivy bair, fair, razor leaf, zard bair, ftilt...). I don't feel like there's too much else to say on G&W. He's just a weird character, and most of your frustration can probably be attributed to mu inexperience.
Do you know what Falcon really, really hates? Short, quick, combo-heavy characters. He infamously gets bodied by them. And we have one of the shortest, quickest, and combo-heaviest of them all. When you get the grab with Squirtle, dair loops should rack on at least 50%. Ftilt combos into everything. Juggle him to death. Get him off stage and edgeguard with bair, nair, and even fair. Keep him in disadvantage. Neutral should consist primarily of ftilt and pivot ftilt, along with fairs, dash grab, and other options that open up combos. I like short hop dairs personally to start things up when falcon gets too aggressive (which is all the time). You can also mess up his flow and recovery with watergun. When switched to Ivy, keep Falcon at range with razor leaf. If you can get him offstage, nair is an unavoidable tool for a free edgeguard, and sh dair at the ledge is pretty easy against him too. Zard relies on a super hard bait and punish gameplan, and that's not hard to do against Falcon's ultra aggressive playstyle. Up smash oos, up b oos, easy grab combos, easy edgeguards... even zard can do well in the mu and that's not something I normally say, although zard is also huge and easily combo'd and that's what falcon really really likes. Basically you gotta play safe with Zard or else you're taking a ton of damage and/or a knee.
All in all, I'd say that your problems with the two are based on MU inexperience more than anything else. Both these characters are a bit underrepresented in the current meta so you're probably just not used to their gimmicks. I'd definitely say that Trainer wins both matchups. I hope this was helpful for you.