I imagine most of us are still working our way towards the end of this game's wonderful story, so for this topic let's go easy on the plot spoilers. Spoiler tags are available for pertinent mentioning, ie. familiars that are only available after a specific story event.
Familiars! the bread and butter of Ni no Kuni. They're alot like Pokemon - you obtain them via a capture method, they level up, are capable of changing their form, have caps on how many abilities they can use in battle, and some of them are even shiny. The big difference being equipment, and their capacity to communicate that doesn't involve saying only their name in alternate tones. I'm sure I don't need to define them any further. You're in here, you probably already know what's what. The Wizard's Companion offers a great summary, otherwise.
I'm about half-way through the game, so I'm no expert yet. I only just achieved the final forms of four of my familiars: Mighty Mite > Dynamite, Sprout Sprite > Sweatpea Sprite, Sea Naiad > Lesser Spotted Naiad, and Strongo > Flourongo. Unique familiars in the wing that make up my party are: Impaler, Cutpurrse, and Bone Ranger. I believe Philip Kollar, who reviewed the game, said he had a Purrloiner aswell, and that's one I recommend to get early on - like Thumbelemur, it has good attack speed and evade stats, and better equip options.
To get the ball rolling,
Who's on your team?
What's your favourite familiars so far?
Which familiars should the rest of us invest into?
What are some effective strategies/combinations to use?