OK, detailed version of my opinion:
Lucario vs Squirtle: From the start, Lucario has an advantage. Lucario is much more capable of surviving than Squirtle, so off the bat, Squirtle will have an uphill battle to even KO Lucario. To compound things even further, Lucario has aura, AKA the ****ing Mechanic that makes Lucario more powerful the more damage he gets, so in an attempt to KO Lucario, Squirtle can end up setting his own death trap, as he has no reliable KO method that works below 100%. Lucario and Squirtle can both play airborne, so squirtle's saving grace can't save him now. Squirtle's last resort is to try to hit and run as much as possible to avoid getting killed. Lucario, wait for it... wait for it...
Lucario 60: Squirtle 40
Lucario vs Ivysaur: Ivysaur performs MUCH differently from Squirtle. While Squirtle is all damage racking, no KO, Ivysaur has several KO moves, especially in that dreaded upwards direction (Uair especially). Conversely, Ivysaur does not have many reliable methods to get to KO point (barring bullet seed and razor leaf, both of which are questionable with Lucario). Ivysaur, does handle being knocked around better (being Mid weight), but sucks when it comes to recovery (as we all ****ing know). Ivysaur doesn't have to worry about Aura as much, but the threat still exists. Lucario's main ace is the ease of Gimping Ivysaur. Outside that, there isn't much of a 1-up. Ivysaur can hit you from a distance, not to mention counter an air game with bullet seed, and a bunch of other ****.
Lucario 55: Ivysaur45
Charizard vs Lucario:
This is a matter of "who hit first?" more than anything else. Both Characters have an above average recovery, can juggle, hate being juggled themselves, and has a deadly ace (easy time Killing anybody vs aura). Charizard has several methods of racking up damage (Flamethrower, rock smash, grabs and throws, and U attacks), along with a lot of KO moves (All tilts, all smashes, Fair, Bair, dair, rocksmash, and fly), and out of those many are quite reliable (Ftilt, Dtilt, Usmash, utilt, bair, rock smash to a degree, and fly, also to a degree). Lucario, on the other hand, can play a rather airborne game, and (barring the fact that Charizard is awkwardly agile), can stay there without a ton of problems. Charizard is heavyweight, which means he'll stay awhile (along with being the most mobile heavyweight IMO), while Lucario has several nasty tricks up his sleeve (Double team). essentially, whoever gets the first shot gets the win (barring tripping or some **** to that caliber).
Lucario 50:50 Charizard
Lucario VS PT
You'd expect that PT would have to use all three Pokemon. However, most good PT's can find a way to use only two, so only their best match ups are used. Ordinarily, it's the average of the top 2. however, we don't have a 52.5 :47.5 ratio, so 55:45 will do.
Lucario 55: 45 PT.