What kind of Jedis were together with Mace Windu in order to arrest Palpatine?

Yeah they were all pretty useless. It was a poorly-designed scene from the start.

See 70 reasons to hate Revenge of the Sith (http://www.chefelf.com/starwars/ep3_41-50.php)
**The Shabbiest Jedi**
Mace Windu decides, after getting information from Anakin, that he is going to confront and arrest Chancellor Palpatine. He picks as his helpers what would appear to be three of the shabbiest Jedi he could find.

>**Saesee Tiin**
Saesee dies immediately. He is technically ranked as a 'Master,' though you wouldn't know it the way he holds his lightsaber in the manner most would hold a vacuum cleaner, yet uses it to even less of a defensive advantage. The novelization goes into great albeit unnecessary detail about how he had two horns but one got cut off in combat but had grown back perfectly so that one could not even tell. This makes one wonder why the horn being cut off was even brought up in the first place.

>**Agen Kolar**
Kolar lasts a second longer than Tiin, but wields his lightsaber even less expertly. By this point, the viewer is wondering if Mace even bothered to find *Jedi* to accompany him to Palpatine's office, or if he just rounded up some panhandlers along the way and handed out lightsabers.

>**Kit Fisto**
Kit Fisto is everyone's favorite Jedi whose name sounds like a bizarre sexual fetish. We know Kit Fisto is going to put up *some* fight based on his major role in the *Clone Wars* cartoon series. However, while Fisto does great things in the cartoon fighting alongside the Mon Calamari and using his lightsaber underwater his technique in the movie seems to more closely resemble that of a frightened, blind gimp than a Jedi Master. Fisto just holds out his lightsaber with a look of total panic on his face. His notoriety from the *Clone Wars* series appears to only buy him a few extra seconds of screen time before finally being struck down.
It's apparent that the intent of this scene was to show how powerful Sidious is. Unfortunately, it fails for two reasons:
1.) We haven't really seen these Jedi do anything worthy of note.
Aside from

Maybe because it was an arrest Windu brought along Jedi masters who held some kind of political rank? Like, "The Official Censurer of Disgraced Jedi" or something like that? It's possible Mace overestimated his own abilities and thought that his power, plus any Jedi would do, so he only brought the necessary officials.

Also: did he think Anakin would be there? I don't remember, but if he thought Anakin would be there to help, he definitely would have thought there would be no problems.

Trainees. Very first day.

Hugely unlucky. Spare a thought for those poor chaps...

They are Jedi masters some are given depth in extended media and the clone wars

The obvious intent was to make it seem like Sidious was so powerful, he could eliminate highly trained Jedi’s in seconds. It doesn’t come off that way though, instead it comes off as pretty lazy directing. Instead, I always thought the movie’s in-story excuse is that the Jedi’s didn’t think this feeble, pasty old white guy would be any threat and were caught off guard by his sudden attack.