Does Straw Hat Pikachu have a lower catch rate?

It seems about the same to me. Pikachus have always been relatively hard to catch.

No, Pikachu has always been a pain in the behind to catch. Ultra balls recommended.

By last event do you mean the pikachu community day? They do jack the catch rates up for community days.

I don't remember if they increased the catch rate for Pikachu because it was so long ago but they have increased the catch rate for every community pokemon since Bulbasaur that I know for sure.
As for the lower catch rate, you're definitely not alone. I frequently use regular razz + great or ultraball for pretty much anything higher than 250CP and I do my best to land a great throw.

Nope. Same as it ever was - catching the electric rat (and all the Starters outside of Community Day) is stupidly difficult. And I'm an idiot because I keep trying to catch them.