Below is a list of the levels and the corresponding breeds that become available.
Level 1: Anura.
Level 2: Crustalli and Velatus.
Level 3: Clunicula, Marmorea, Puncti, Tribus (must trade or get within first week of games release), Glacio (only at Christmas), and Lanterna (must trade or get during the week of Halloween).
Level 4: Zebrae, Adamantis and Africanus.
Level 5: Partiri, Nasus, Roboris and Bovis.
Level 6: Mixtus, Calyx and Viduo.
Level 7: Stellata, Spinae and Serpentis.
Level 8: Nimbilis and Cesti.
Level 9: Amfractus and Sagitta.
Level 10: Sol and Ornatus.
Level 11: Lucus and Ligo.
Level 12: Corona and Arbor.
Level 13: Ocularis and Insero.
Level 14: Pingo and Biplex.
Level 15: Floresco and Calvaria.
Level 16: Veru and Magus.
Added by: Sanzano Jul 17th 2012, ID#1128