[TokuKnight89]

I don't claim the following to be the absolute definitive regarding the list you requested, but it's something to start with. Some are necessary, and others are just worth seeing. To keep the surprise (such as with Megazord debuts), I won't include reasons for significance:

- Force From The Future, Pt. 1

- Force From The Future, Pt. 2

- Something To Fight For

- Ransik Lives

- A Parting of Ways

- Jen's Revenge

- The Time Shadow

- Future Unknown

- Uniquely Trip

- Worlds Apart

- The Quantum Quest

- Clash For Control, Pt. 1

- Clash For Control, Pt. 2

- Trip Takes A Stand

- Quantum Secrets

- Movie Madness, Pt. 1

- Movie Madness, Pt. 2

- Frax's Fury

- Dawn of Destiny

- Fight Against Fate

- Destiny Defeated

- Undercover Rangers

- Beware The Knight

- Time For Lightspeed

- Circuit Unsure

- A Calm Before The Storm

- The End of Time, Pt. 1

- The End of Time, Pt. 2

- The End of Time, Pt. 3

Hope this works. Remember some might still be filler or the debut of a new Zord or Combination or Weapon, but even if it's filler, it's good or amusing filler which may play into any discussion regarding Time Force. Others are crucial to a story arc or set the scene regarding upcoming events.