Can a wizard tell an undead that he created or commands to follow the orders of a teammate?
I don't see why not. "Obey him" is a pretty simple instruction that even skeletons and zombies should be able to understand.
Whether or not a mindless undead can be told to follow the orders of another is debateable.
Following the Control Undead spell (and by extension Command Undead feat) mindless undead automatically understand you, because of the spell.
As such, it stands to reason that they do not understand commands from others, without understanding that language.
A more interesting would be, how difficult is it to transfer actual controlled HD of an undead from one willing caster to another...
I think it is quite simple. If you use Command Undead (spell or feat) to gain control over them, and he removes his control, then they are all yours. You cannot tap into the animate dead control pool, apart from actually animating them yourself.
A more interesting question would be, how difficult is it to transfer actual controlled HD of an undead from one willing caster to another...
"Hey youse guise. I order you to allow yourselves to be controlled by this fine gentleman right here" (read: Voluntarily forgo your Will save against his Command Undead).
Easy peasy.