I have to move some three year old fruittrees from a wide open field into my rather small yard, where I want some espalier trees. Since these trees were planted in an open field, they have a normal branch structure. Digging them up will probably necessitate heavy pruning in any case. Should I just cut off branches that don't fall into the espeliar plane, or what? Gradually remove misplaced branches over a few years? Cut them back hard and let a new set develop?
The trees in question are semi-dwarf and semi-standard peach, apple, pear, plum, and cherry trees.
You could just prune a lot to keep the size down all around. I haven't done espalier because it makes trees look tortured and unnatural to me. But I know most people don't feel that way, and it's a useful and productive method in certain situations. I have one plum tree that's too close to the house. I prune it in a fairly flat shape, but don't train it. I'm growing a seedling peach in front of it and will take the plum out in a year or two. It was supposed to only get 10' tall. It got that tall the first year. It doesn't produce because I have to prune it so much to keep it from damaging my gutters.
What's your plan for moving the trees? That's going to take a lot of digging.
When you dig these trees, decide which side will go against the wall by looking for nicely opposing branches, those will be the espalier branches. The side that will go against the wall, trim off all those branches, leaving the rest for now.
I recommend using some Elmer's white glue as a temporary cover for the wood exposed by the pruning also be sure and leave the branch collar intact so the tree can seal itself over time. The glue just prevents decay or infestation via exposed heartwood.