Does combining Wellbutrin and Zoloft help with the sexual side effects and possible weight gain?

Hi, Blessed!
Studies have shown that Wellbutrin when used to treat SSRI induced sexual dysfunction caused about a 50% improvement within the first several weeks in most participants. It's also considered to be weight neutral itself but probably wouldn't affect weight gain from other antidepressants.
Only about 10% of Zoloft users will experience these side effects and Zoloft can also cause decreased appetite/weight decrease in some cases.
As masso pointed out, you wouldn't want to combine these two antidepressants unless your doctor has determined that any benefits would outweigh the potential risks.

Interactions between your drugs
Major
buPROPion sertraline
Applies to: Wellbutrin (bupropion), Zoloft (sertraline)

Talk to your doctor before using buPROPion together with sertraline. Combining these medications may increase the risk of seizures, which may occur rarely with either medication. In addition, buPROPion can increase the blood levels of sertraline, which may increase other side effects. You may be more likely to experience seizures with these medications if you are elderly, undergoing alcohol or drug withdrawal, have a history of seizures, or have a condition affecting the central nervous system such as a brain tumor or head trauma. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. You should avoid or limit the use of alcohol during treatment. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Source: https://www.drugs.com/interactions-check.php?drug_list=2057-1348,440-203