for decorations that need to be really hard do you still need to add Tylose to the fondant or will the gumpaste be enough?
No you don't need to add tylose when mixing fondant with gumpaste.
I sometimes add Tylose to my gumpaste and fondant mix. For different reasons - I want it to dry fast and really hard or I need to use pre-colored fondant to achieve the right color but need the hardness of gumpaste. Itä's harder to get gumpaste dark colored so I mix it with black fondant for example before I add extra black coloring. And I then need in some Tylose to make it hard.
But generally you don't need to add it to you mix
what are you making?
a fondant gumpaste mix will do the job, but gumpaste alone will be stronger and dry faster.