Animal-type guardians are fine, as long as you keep them within a G, S, T or J type.
Sorry if my response is bad, just got back from work and so tired. >~<
Which I forgot to say. Ehm.. its fine to join midway.
Also Sova, as you said you couldn't see some characters for hire, can you see all the EX-types or do I need to replace some of their links too?