This 3-Up Minor Creature page from our Dungeons & Dragons 5th Edition Critters, Companions, Conjurations and Constructs (C4) Addon Pack is handy for keeping track of multiple, relatively simple creature statistic blocks.
It’s particularly well suited for Familiars and the lower CR Druid Wild Shape forms, but it also makes a great place to keep track of mounts, pets, or even the combat statistics of objects brought to life with the 5th level Animate Objects spell (see Animate Object Statistics in the D&D 5e SRD)