Ivysaur: 8% base-capture rate
Charmeleon: 8% base-capture rate
Wartortle: 8% base-capture rate
Raichu: 8% base-capture rate
next slide will load in 15 secondsSkip AdSkip AdClefable: 8% base-capture rate
Ninetales: 8% base-capture rate
Arcanine: 8% base-capture rate
Gyarados: 8% base-capture rate
Dragonair: 8% base-capture rate
next slide will load in 15 secondsSkip AdSkip AdGengar: 8% base-capture rate
Venusaur: 4% base-capture rate
Charizard: 4% base-capture rate
Blastoise: 4% base-capture rate
Dragonite: 4% base-capture rate
next slide will load in 15 secondsSkip AdSkip AdWhile it doesn't have a low capture rate, Abra has the highest flee rate in the game, at 99%. So if you don't catch it with your first throw, it will probably disappear.
These percentages are only the base rates, which means catching these Pokémon gets even harder the more you level up as a trainer in the game.
And in case you were curious, the easiest Pokémon to catch in the game is none other than Magikarp. Its base-capture rate is 56%.