Thanks for the reply! It's interesting that trust evolves virus types. In the Vpet virus evolution was random with care mistakes, training, egg type, and win streaks influencing the mon it becomes but not 100% dictating it most of the time. There's always a risk of death from natural causes before it can evolve, too.
Which items recover trust?
A win streak is not very reliable for recovery. Losses make you lose trust badly and you may have to use expensive bandaids or medicine to heal. In my opinion battle is a big risk with low rewards in regards to recovering trust.