What fish do not need a pump for example the betta fish or Siamese fighter What about guppies?

I don't know what beta fish are but I can assure you something.

All fishes need a pump for a healthier living.

Only one Siamese fighter can be put in a tank. It is better to use a bowl for this. Water should be changed every 2 weeks. If these conditions are satisfied the fish will be fine.

I am a successful breeder of guppies. As far as I know It is is advised to have green plants rather than a pump in their tanks.