How to upgrade the pets?

[Byson]

As title, where could we upgrade the pets? I've upgraded them several times, but still don't figure it out which waypoint could trigger the event.

[Stormfox]

Sylvie's Owl upgrades automatically through her talents. Of the others, one per run can be upgraded by the Pokemon Trainer event that IIRC happens in the southwestern corner of the mountains biome.

[Chairman]

Sometimes the monster trainer can appear in the Green Portal right after Gruklis node I believe, I’ve seen him there quite often, another spot is like Stormfox said in the Red Portal near the camps leading up to the Ritual site I believe

[Psylisa]

Green - event right after Grukli
Red - A Special Team node
Blue - Squirrel Trainer node

Never seen one in Act 1 or Act 4. Do note that due to madness/corruption, if you rescue a pet during your run, you can in fact get the upgraded version by chance. So rescuing Betty in Act 1 can yield the upgrade immediately. Had a FANTASTICALLY easy run when I nabbed an upgraded Betty on Nez in Act 1.

[HAWAIIANpikachu]

also in the Squirrel Trainer if you crit success the catch you will get an automatic corrupt version.