If it's not Royal, it is a waste. 

They take too much EXP to level.
They don't stay transformed nearly long enough.
The enemy AI will target an untransformed Laguz before most any other unit/condition in the game.

I would agree, the only laguz worth taking into the final chapters (minus the ones your forced too), would be the royals (with the only maybe being Nailah because of her lower level).

@Pinab, the only thing that Giffca is good for is the item he comes with, other than that he is completely overshadowed by the fact that Caineghis is a royal and can always stay transformed.

@Khuutra, pretty much every master skill is awesome and mostly OHKO every character in the game.

Sothe's master skill Bane would like to say "hi" as it likes to keep people alive

How do I get Volke?

And look, all I'm saying is that right now, with some Olivi gras, Ranulf is awesome. Even without it, it takes three turns for him to max out his transformation gauge and it will last him through a lot of killing.

All of the cats fill up and use their guages really quickly, but every non-royal laguz is basically useless compared to any of the royals (not counting the laguz gem).  The royals are allowed to stay tranformed for the entire level, so basically they do not need to worry about untranforming in the middle of the enemy turn (which Ranulf and other cats do very quickly).  You will find that the dragons you get (although slightly underleveled when you get them) stay tranformed the longest of all non-royal laguz.

Basically, I would not really waste any experience on Ranulf, you will see how bad he is once you get Tibarn (who is amazing) and Caineghis.  With these 2 laguz, there is no reason to even think about wasting space on the other laguz characters.

EDIT: To get Volke, all you need is some money on the level he appears in.  He's actually really easy to recruite, and it is quite obvious when your in the correct level (mainly because he starts right beside you and stands there the entire level)

I lost Fiona in the distraction of the Begnion army.

I'm not done with the mission yet. But.... it had to happen. I'm sorry, Fiona. Goodbye.

Time for a reset then.

Too late.

SHould.... should I not have obeyed that command?

TOO LATE TO TURN BACK NOW!

Oh wait, Fiona... Nevermind. I usually bench her and Meg for the whole game. You can live without them.

Although... your Fire Emblem street cred is gone.