Can a child with pneumonia go swimming?

Seriously ?? Why would you ever consider this ? The child need not be exposed to who knows what in the pool/ocean water, possibly aspirate water, or stress the lungs with exertion. Might want to ask MD for strict guidelines for activities. Good Luck.
Yes. If the child is well enough to be active and go out, they should be fine going swimming. Depending on whether they are on antibiotics or not, be aware that while on some antibiotics, exposure to the sun needs to be limited.
Not a good idea. Theoretically, you can, but pneumonia can be a major medical problem and even a fatal complication. Be patient.