I know when building your team you can add 3 objects but is can they be of any waight or do they have to be like 2 light and one heavy?

It has to be

1 light/ultra light
1 heavy/ultra heavy
The last one is your choice( it can be light, heavy, special, relic, etc)

You need to use one light, one heavy, one of your choice. You could do 2 Ultra Lights and an ultra heavy for example or vice versa. Same as being able to use 2 lights and a heavy or vice versa.

Sniped

So can I use 1 light an 2 ultra heavy?

Yes, because Ultra heaves are considered a heavy object with additional rules.

You can, but you don't have to...

You can add up to three objects, but you could choose to use only one or two.

If you use one, it can be any type, and if you use two they must be different from each other.

In your above example you accomplish this by having your "first two" objects be a light and a heavy (ultra or otherwise).

This came up last week.

I was trying to use an Ultra Heavy, an ultra light and a relic. Appearantly the ultra heavy and ultra light aren't standard objects.

Guess I need to tell them they where wrong.

The tank turret from the Hulk set is a special object, unless they have made up some errata for that, but the recent ultras that have appeared in the starters are standard objects.

But the only time it matters is for sealed. There is no restriction on the number of special objects that you can use.
The only limit is on the number of immobile objects. The rules only allow for one of those on a force.

Immobile objects may be special, but a special object doesn't have to be immobile.