This is based on the standard frog Familiar from DND 5e. The standard stat block would be the same for the familiar itself, below are the quick construction guide for the bat.
Species attributes:
- Speed: 25 ft., climb 15 ft., swim 25 ft.
- Amphibious: You are capable of breathing in water and air.
- Of Land and Water: You are capable of breathing in water and air.
- Chemical Sensitivity: Gain advantage when identifying alchemical substances and potions.
- First Level Diverse Features: Jump, Slippery
- Recommended Diverse Features for 5th and 10th level: Natural Weapon, Blend In, Climber, Darkvision, Hunter, Natural Climber, Poisonous Bite, Poisonous Body,