Does the Phone Need to be in Mint Condition?

Your phone is going to be re-used, re-conditioned or recycled, so it needs to be in working condition, displaying nothing more than cosmetic damage, with a working battery and able to be switched on.  If it's in tip top condition you'll get the fully working model value. 

Do I need to send the charger?

You don't usually need to send them the charger but if you do most of the mobile phone recyclers will recycle it properly for you (otherwise you could keep it as a spare or sell it on eBay).

What if the phone is damaged?

Want to sell a damaged phone? Most providers will consider non-working phone handsets and give you a reduced price for these (expect to get around 10-50% less) or at the very least will re-cycle the phone for you.

The types of damage they look for include badly damaged casing, a locked pin or failure to power up. Water damaged and broken phones with unresponsive or cracked screens will probably earn you nothing.  Do't waste your time sending in a phone that's got no use.