The Mach Bike is faster than the Acro Bike, and the Mach Bike allows you to go up slippery muddly slopes whereas the Acro Bike doesn't. Also, although you can ride the cycle path on an Acro, you can only set a record speed on a Mach Bike, because the Acro is much slower/easier to manouvre.
Yes
Rayquaza is in Sky Pillar, you'll need a Pokemon that knows surf to there, and also the mach bike.
Mauvile city at the bike shop.
There's a bike shop in the city with the electric gym. Go inside, talk to the shop owner and choose your bike (mach or acro).
use a mach bike
There is not a bike voucher in Pokemon sapphire
The Acro and Mach bikes are only in Ruby, Sapphire and Emerald. There's only one bike in Crystal and you can get it in Goldenrod
in the left side of the safari zone, where you need the MACH bike, there is Pinsar this is the Pokemon that you can get there, the equivalent to the other area is phanphy.
Mach Bike Section of the Safari Zone
your right but you need the mach bike not the acro bike because i do it with the mach bike and works for me.
heres only a bike no acro bike or mach bike
The Bike Shop...........