Tail Spear: Again, you actually can't tribute from the graveyard. Just have it use tributes from tge hand since the in hand cost would balance this out. Also 1000 atk plus piercing on what is effectively a revival card seems a little too strong and your monsters are big anyways.

Supreme Tyrant Dragon: Still needs a once per turn clause and have its attack restricted to only monsters. Better yet have it so it can only attack monsters.

Tyrant Dragon Overlord: The wording you want is "This card can be tribute summoned but tributing dragon-type monsters from your hand and/or banishing dragon-type monsters from your graveyard". Also summon protection is superbusted on card that is also protected from spell-based spot removal.

Edit: Was busy composin when you posted above. Sorry if I got preachy.