Hmm, tough one. The default answer is "follow it up the chain" - if your boss isn't doing the right thing, talk to their boss, and so on. Another approach is to talk to the manager of the team who's leaning on you, and let them know (if they don't already) how much they're depending on you and that you should really be in that team. This can cause drama with your immediate boss (they're seen as 'poaching' you) but if said boss doesn't care then this might not be a problem.
Of course, by the time you have upper management yelling at you because "several teams are waiting on you", the response becomes "why have you allowed several teams to become completely dependent on one overworked person?"
The other, more drastic solution (as someone else said) is simply to move jobs. This can be the only way to fix the issue if the entire management structure is corrupted and you don't think it's fixable from within. You could even just leave, start a consultancy company, and let the second team know that you're available for hire when they need you.
Of course, by the time you have upper management yelling at you because "several teams are waiting on you", the response becomes "why have you allowed several teams to become completely dependent on one overworked person?"
The other, more drastic solution (as someone else said) is simply to move jobs. This can be the only way to fix the issue if the entire management structure is corrupted and you don't think it's fixable from within. You could even just leave, start a consultancy company, and let the second team know that you're available for hire when they need you.