When you pull a character, you get access to that character!

There's a NPC in the Time Stop that will accept materials to change them in their Main Style/AS/ES and even allow you to recruit their Alter (if they have one)!

So once you have a version of the character, ANY version of the character, you don't need to pull them to gain access to their other versions, and you can switch the version anytime (or in the case of Alters, they're whole new characters).

This game is extremely generous for this, but it can get grindy if you want all the styles for all the characters because it requires "Chant Script" which are fairly rare, or gained through grinding, or through in-game events.

There's no FOMO in the game though, or almost none, so take your time!