I stuck Coeurl in pretty early in the process, though the order could easily be changed around. Coeurl's whole deal is attacking swift, with rapid gcds at lower potency.
For all of the Beast's Calls, the top line is the Beastmaster's actual actions, below are the actions the Beast takes.
The top left is a unique action to assign to call the Beast, with a longer recast time. The exact length of the recast timer, i'm not positive about since I can't exactly playtest it but there are several Beasts with which to choose from, so it might end up being about right.



I mostly chose Fenrir for the concept because a beast of the same type was used in Zadnor, and I thought it was fun to use here. Fenrir's weaponskills are a longer combo, that hits an area rather than being single target, and also grants a damage buff (for now). I have been working with making a few of the gapclosers as weaponskills that can get used anywhere in the rotation, mostly with how the animations might work. Could change very easily for most of the Beasts.



I placed Dawon at level 50, based on Lyon's pet, though smaller and younger. I couldn't find what species they are to put here but something akin to that.



Manticore is another beast I added because of Lyon in the fight with Dawon. Could also use something more like Gowrow, the Crocodile type of diresaur-like enemy.
Their whole deal is strong, heavy hits, but with cast times as a wind-up on a longer GCD.
These should be slightly above proportional for the increased cast time, so it's not a loss to actually use.



Malboros are pretty iconic so I wanted to include one here. Single target weaponskills with it do have a slightly increased range.



Behemoth's the last one I added for this concept because it would be fun to team up with a Behemoth. They have a longer, slower combo.

That would be all the Beasts themselves I added. Again, this is mostly to show how the general combat flow might work, to show how it could be implemented. The 6 Beasts I chose don't have to be the ones that actually get used, of course.