If you've got a full-frame camera, as above the basic kit would be for most people:
24-70 f/2.8
70-200 f/2.8
50mm f/1.4 (or better) or 85mm f/1.8 (or better)
Also, for professional shooting you absolutely need a second body - it saves losing shots when changing lenses, and means you can keep going if your body fails. Plus plenty of storage and batteries.
For portraits, either of the following if on full-frame (if you are just looking for one lens)
70-200 f/2.8
85mm f/1.8 (or better)
If on crop-sensor cameras, either of the above lenses would still be good for portraits, but the 50mm f/1.4 (or better) would also do nicely.
For weddings on a crop-sensor camera, the following would be a good combination
17-50mm or 17-55mm f/2.8
70-200mm f/2.8
35mm f/2.0 (or better) or 50mm f/1.4 (or better)
Despite the above 'standard wisdom', I shot a wedding with two bodies on me, one of them holding Canon's 70-200mm f/2.8 IS II, which is a beast and got too heavy by the end of the day, and to be honest I found the depth of field too shallow at 2.8: so personally (at least for that wedding), I wished I'd had the lighter 70-200mm f/4 IS instead.
If you can add more lenses to the above choices for weddings, the next would be macro capability and ultrawide or fisheye.
None of these lens choices are set in stone; there are still photographers who will shoot a wedding - and do a great job - on full frame with *only* a 50mm lens. So, it's a question of style too. However, you must, must, must have equipment redundancy (two bodies, and some amount of backup lenses).
If I *had* to choose a budget kit to shoot a wedding with, I'd have two modern crop bodies, one with a 17-50 (or -55) f/2.8 - maybe at a push Sigma's 17-70mm f/2.8-4.0; and one with an 85mm f/1.8 or 100mm f/2.8 macro, and then a 50mm f/1.8 as backup or for when the light got really low. Plus at least three spare batteries and a heck of a lot of memory cards. (As budget crop bodies wouldn't have dual card slots, I'd go for medium sized cards and change them semi-frequently, so in case of card failure I didn't lose too many images. Much better if you have a body that can record to two cards simultaneously, but not possible on a strict budget). If you can't buy and/or hire at least this amount of equipment ... don't even think of charging someone to shoot a wedding.