I've never used anything but the vitamin/electrolyte starter. Usually start a little light of the full recommended dosage if everyone's well on arrival. (If not, a little sugar in the water the first day or two in addition to the V/E mixture has always worked just fine to get them over any travel stress. (Keeping in mind that they will grow in spurts) I usually lay off of it after the first week or so, but keep it on hand to supplement the water if they seem to be slowing down due to any heat or other stress.
I think you can use some pedialyte if you don't have the powder. A bunch of my new chickies have pasty butt, so I added polyvisol without iron in their water. Also ACV works great, but it needs to be the good one with the Mother, like Braggs organic.