Scyther is easy if you have some strong Golems. Stone Edge gets ahead of the clock really well. Tyranitar is good, great against Night Slash, but not so good against X-Scizzors. And if the Boss has Fury Cutter, that makes it really easy - Fury Cutter is a quick attack that does little damage. The Gym AI attacks once every two seconds, so the damage is tiny.
You did well to get 2 TMs from two level 3 raids.
Omastar is tougher. Try Machamp or Gengar (very manageable if you have a Lugia and a few Espeons.)