Trombone

Grades 5-7: Bach 6 1/2AL (small shank)
Grades 8-12: Bach 5G, Hammond 12ML or 11ML (small or large shank, depending on instrument)

Euphonium

Grades 5-7: Bach 6 1/2AL (small shank)
Grades 8-12: Schilke 51D, Hammond 11L or 11XL (small, medium or large shank, depending on instrument)

Tuba (BBb or CC)

Grades 5-8: Bach 18
Grades 9-12: Conn Helleberg or Perantucci PT-50