Any champ can snowball if you build the right damage on them, but with some its easier then others, those that combine damage with mobility and CC are the best at it. For example; you're gonna have a harder time snowballing Soraka then Akali. XD But its not impossible.
Its more about knowing how bots move and react, being able to lure the bots away from their tower into stupid positions gives you the best chance of killing them. And know how their behavior changes as the lose health and the threshold for when they start to recall. Another important thing to remember is the lane you go to depending on which side you play, go botlane if you are Red side and go Top lane when you are Blue side, due to the layout of the map those side/lane combinations gives you the easiest way of sneaking in a kill when the bots go for a recall, remember to use your trinket in their bush for vision and stay out of sight.
Your next most important asset if your partner, learn to chain CC with him/her and you'll be raking in the kill/assist gold over and over. Especially because the bots will be coming to your lane in greater numbers due to the tower pressure you'll be creating. Because its a bot game you don't have to care about meta or whatever and can take any combination of champs anywhere you want. So experiment with this. (I find that the combination of Lux and Lulu is an absolute murderfest on the botlane.)
And don't forget to roam when you expect the enemies on the other lanes to be in bad positions.
Another useful thing is to run the summoner spells Teleport and Flash or Exhaust. Teleport for getting across the map fast to get more kills, Flash to get in that last crucial hit before they escape, and Exhaust to easily win fights and make their escape harder while you kill them faster.
From your list I think Ezreal, Tristana, Lulu and Ashe have the easiest time snowballing.
I would also suggest you pick up Poppy, she is fun to play, cheap and super easy to snowball with, Max Q, get 1600 gold buy sheen, boots and armor on her and you will murder everything, just continue a bruiser build.
Good luck.