Squirtle can be obtained from Genetic Apex Pikachu Booster Pack in the Genetic Apex Set
Heres my rundown of what you should check out: The Reaver Cleaver lets you turn one of your creatures into Old Gnawbone
The nice thing about Gabite is that its attack, Slash, deals 60 damage for just two Energy, a Water and a Fighting

Alchemist's Gambit All in Good Time Alrund's Epiphany Avatar Kuruk Capture of Jingzhou Chance for Glory Emrakul, the Aeons Torn Expropriate Final Fortune Frenetic Efreet Avatar Gonti's Aether Heart Ichormoon Gauntlet Kang the Conqueror Last Chance Lighthouse Chronologist Lost Isle Calling Magistrate's Scepter Magosi, the Waterveil Medomai the Ageless Mu Yanling Nexus of Fate Notorious Throng Otaria Part the Waterveil Perch Protection Phone a Friend Plea for Power Ral Zarek Regenerations Restored Rise of the Eldrazi Sage of Hours Savor the Moment Search the City Second Chance Seedtime Stitch in Time Teferi, Master of Time Teferi, Timebender Temporal Extortion Temporal Manipulation Temporal Mastery Temporal Trespass Time Bends to My Will Time Sidewalk (playtest) Time Sieve Time Vault Time Walk Timestream Navigator Twice Upon a Time Ugin's Nexus Ultimecia, Omnipotent Wanderwine Prophets Warrior's Oath Wormfang Manta
Ob Nixilis Commander 2016 The latter two arent actually reprints
Changes You Can Make One obvious issue with this deck could be the use of legendary creatures in bulk, as you can only have one copy of a unique legendary creature active on the battlefield at any time