If Grievous can just shoot at him, his jetpack is less effective and just a means of getting out of range of his lightsabers. Neither of the combatants are particularly fast, but Jango is not going to be able to relieve Grievous of his lightsabers. Obi-Wan only did it because he's a Jedi Master, has the Force, and has a lightsaber. Jango fet has a lot of nasty toys, but Grievous would slaughter him.
Rocket launcher, Grievous could evade; Obi-Wan narrowly did so, and if we're talking CW Grievous, the rocket is moot. If Grievous is in his wheel bike, even more so moot. Grievous is too fast for Jango's rockets.
Flamethrower might be a tad more difficult, but Grievous isn't exactly flammable, and his organs are protected against a weapon like this, I'm sure.
Dart thing? Jango would need a lucky shot to get that saber dart into Grievous without being stealthy about it. In the middle of combat, damn near useless.
Blasters, Grievous can deflect, and is heavily armored anyways, it seems.
Meanwhile, Jango has no defenses against lightsabers other than 'Stay away.' He is wearing armor as well, but he's not blaster-resistant. Grievous just wouldn't care if he was shot at and the bolt hit his armor; he has no feeling in 'body' cause it's all synthetic. Jango probably would and be hurt by it. Too many shots and he goes down. We've all seen how well stormtrooper armor withstands bolts.
And if it comes to a contest of vehicles, Jango's backpack is going to have less fuel than Grievous' bike. Eventually, he'll have to land. Grievous, however, has no need to stop his bike, which has cannons as well.
The real question is, who'd win the space fight? 😉