Constitution
Beasts are a healthy lot with an all-natural diet, there's no Constitution modifier lower than -1.
Constitution 8 beasts
- bat
- frog
- hawk
- owl
- raven
- scorpion
- sea horse
- spider
- weasel
Constitution 9 beasts
Wisdom
Only four beasts have a -2 Wisdom modifier.
Wisdom 7 beasts
- giant boar
- giant centipede
- giant fire beetle
- quipper
Wisdom 8 beasts
- camel
- crab
- frog
- lizard
- scorpion
Wisdom 9 beasts
- boar
- giant crab
- giant scorpion
- pteranodon
Charisma
There are plenty of Intelligence 1 beasts, but there are no Charisma 1 beasts. Oozes like the gelatinous cube have Charisma 1, but even a spider needs to somehow secure a mate for sexual reproduction.
Charisma 2 beasts
- crab
- quipper
- scorpion
- sea horse
- spider
Charisma 3 beasts
- constrictor snake
- frog
- giant centipede
- giant constrictor snake
- giant crab
- giant fire beetle
- giant frog
- giant poisonous snake
- giant scorpion
- giant toad
- giant wasp
- lizard
- poisonous snake
- weasel
Only the quipper is at the bottom of all tiers
The quipper has -1 to Con saves, -2 to Wis saves, and -4 to Cha saves. (The more traditional frog is only two out of three - it has a -1 Wis modifier.) A quipper can 'hold its breath' - so to speak - outside of water for 30 seconds, and drops to 0 hp 1 round after that, which ends the polymorph spell, so put it in a fish bowl long enough to do whatever you need to.
Quippers, frogs, and any other beasts with Charisma 3 or lower literally can't meet a spell save DC of 17 against the imprisonment spell, effectively guaranteeing the caster will succeed.