Do I really need a terrain markers, heavy objects, light objects and bystanders to play the game? How about if I don't own any of those, but my figure is summoning a token which is a bystander or my other figure has super strength and needs to pick-up an item? I'm new to this hobby and I need clarifications. Please, enlighten me guys. Thanks

You do not have to include any objects on your force, so you don't need object tokens.
Bystanders are characters, so you don't have to use those.
If you want to destroy walls or use powers like Smoke Cloud or Barrier, then you do need terrain markers.

If there is an actual cardboard element (like White Rabbit), then the figure comes with it. It can always be created with print and play, though.
Most characters with powers like this don't have a physical representation, so you would just use something like a quarter. (There are some people, like "clixaccessories dot com" who make tokens which are good for these purposes.)
You are never required to pick up an item. If you want one, though, then you would need to have the objects.

Thank you for the clarification

You are never required to pick up an item. If you want one, though, then you would need to have the objects.[/quote]

Can I represent these objects with a die or a quarter?

Can I represent these objects with a die or a quarter?[/quote]
If you are talking home games, then you should be ok. If your opponent objects, you should get new friends as those ones are bad people.
In an official tournament, you may have issues.

In any case, I'd recommend using something with color coding.

oh nice. thank you very much