Can't vouch firsthand for the zebras, but yo-yos would do just fine. I am particularly fond of yo-yo's, and have five in my living room aquarium now.
Haven't kept the zebra loach (Botia Striata) before. They are rare finds in pet stores in my area (yo-yo is not exactly common, but much more common than zebra). I have rarely seen more than one or two Botia Striata at a time, if they are available at all. Some report they are very peaceful, some say they can be temperamental and mildly aggressive. As with most loaches, if you keep them in a shoal of 5 or 6 they will probably spend most of their attention on each other. They will establish a "pecking order" among themselves and there will be some minor toussling when that order is challenged or reinforced, but it's really not a big deal. This is pretty much the case with most loach species. I'm sure they'd do alright with tiger barbs in any case. Whether you choose yo-yo or zebra, I'd go with a shoal of at least 5 or 6 - not less than 4.
One thing I wouldn't do is mix them though. I'd encourage you to choose yo-yo or zebra and go with it, but not both. In my experience (and some may disagree) mixing loach species often results in frequent skirmishes between the species; I figure it's just an increased compulsion to reinforce pecking order between species. That's just what I've seen. The more passive loaches (like dojo) might mix better, but still I'd be reluctant.
Hope that helps.
pendragon!