one mybb theme uses stylesheets for colors positions tables etc etc
the tabs plugin it also haves a stylesheet file
if i install mytabs on my forum ( or any forum with default or costum theme) i can assure you that it will look very bad
after installin mytabs plugin you will have to edit the stylessheet to get a nicer look
so my answer is any theme, as long as you edit the style for the tabs ;)
You need help on mybb???
ill help you.Post on support forums and give a live url for your forum!!