This is a very interesting thread ^^ Thanks OP!

Lots of nice ideas in here, but I'm still with the perma-pet crowd . It is a pet class, so it's only logical that a pet should be present (whether permanently or for a limited period of time).

Putting everything into consideration (mainly talking about SMN here), why not have a SMN class that has a pet present AND has a powerful 1-shot move? Too powerful? not if balanced properly! Please hear me out.
  • Summoning a pet costs the SMN MP, and drains TP while it's present (a specific summon can stay for a maximum of 15-20mins after being summoned before it disappears, lore-wise also makes sense because their presence drains aether)
  • TP (or maybe they call it SP for summoning points?) is drained at different paces by different pets. (stronger drains more)
  • Each pet is it's own entity when summoned! It has it's own HP/MP.
  • Each pet has a set of 7 moves (just like what Tonkra said) to be unlocked, the more you use the pet the more moves you unlock. The final move to learn is obviously its "signature move".
  • Using these moves consumes the pet's MP not the SMN's. There should be an ability for the SMN to transfer his MP to his pet and vice versa.
  • Each pet has a "power" gauge that builds up during battle. When it reaches maximum (gauge starts flashing and depleting), then we can use the final move (before the gauge depletes, 30secs window?). However, the pet will disappear after using it and be "exhausted" for a set period of time. Other pets can be summoned in after it if the required MP/ TP are available. If gauge depletes before being used then, Sorry... you missed it
  • If the TP is fully drained while a pet is summoned, the pet will disappear and be "exhausted" for a set period of time.

This way your main strength is your pet (the way I think it should be), and taking advantage of it's full power is the main key (the idea of the gauge is so that not everyone starts spamming "Hellfire" the moment they see a boss). I'm not saying this is perfect, but it's some sort of a middle ground.

I really hope it's a perma-pet class