From the synopsis, they are straight adaptations of Shinkenger Acts 17-19 which means that 4 episodes (13-16) from Shinkenger will be skipped...
Below is a review of what happened in the Shinkenger episodes and the possible reasons for skipping them:
Act 13: Heavy Cry
This was the girls' focus episode for Pink and Yellow. The monster of the week resorted to stealing parents by replacing their children with white dummies (mannequins), so that the heavy cries of the children could flood the Sanzu River fast. Therefore, Pink and Yellow took on the role of babysitting the abandoned children, as well as fighting the monster when it managed to paralyze the male Shinkengers by attaching the similar red dummies on them.
Obviously, this episode would be skipped because the concept was rather weird for American audiences. Plus, there are a lot of scenes which are kinda obscene with the dummies (see the above screenshot). Hence, to adapt the episode would involved a lot of re-shooting and focus on female rangers was never a priority in PR.
Act 14: Foreign Samurai
A foreigner by the name of Richard Brown approaches ShinkenBlue and begs him to teach him the path of a Samurai, which resulted in a comic relief episode. However, Richard Brown was able to inspire ShinkenBlue to defeat the monster of the week when it overpowered all the other Shinkengers.
Now, this would be a great episode to tie-in with Bulk and Spike's "Samurai Training" therefore, I am not sure why it was skipped. Perhaps, this will appear in later episodes because PR has shuffled adaptation orders in the past as well.
Act 15: Imposter, Genuine, Big Catch
Chiaki (ShinkenGreen) gets frustrated at his own incompetence and runs off during a training. During an attack, the monster of the week changes his appearance and posed as Chiaki in attempt to divide the Shinkengers. It is up to Chiaki to turn the events around and save the day by mastering the "Shirahadori".
This would have been a fun episode but it probably would have conflicted with Mike's development as he was nowhere as playful as Chiaki, kinda like when "Forest for the Trees" (Episode 8) was adapted.
Act 16: Kuroko Power
ShinkenBlue, Green and Yellow realized the help that the Kurokos (stage hands in black) rendered behind the scenes so that they can concentrate on defeating the enemy.
Needless to say, there are no "Kurokos" in Samurai so this episode is redundant anyway.
To end off, more episodes would probably be skipped over as well since the total episode count for Samurai is only 40 episodes compared to Shinkenger's 49. Therefore, it is only natural to not adapt everything, unless Saban is going to follow Disney's route to squeeze 2 episodes into 1 like Mystic Force.
