As he is trying to lower TSH I assume he has a high reading, which is potentially from low T4/T3
In which case Tyrosine, selenium, iodine are good ideas
Although OP was fairly unspecific, are you just trying to slow metabolism in general (hard gainer?) or trying to treat a high TSH test result
For what it is worth PPARy is competitive with Thyroid hormone and notable lowers my T3 when using certain supplements