The time is at night, and hamsters are basically sleeping in the morning, which is not lively.
2.
Bring some breadworms to feed. Hamsters who usually grab food are stronger.
3.
Observe eyes, ears, buttocks, abdomen, limbs, etc. Hair is not knotted and yellow, eyes are bright, ears are clean and you are in good health at ordinary times.
4.
The bigger one is usually the stronger one in the nest.
5.
Look at the eye margin.