Since he doesn't have any particular mechanic he won't be a top tier unit (in the standard mode, maybe in the proud battle he can) but he's more than viable for a Top 10k. Calling him "trash" is just wrong
For old Zenkai unit the only thing you can do is the "ultra space time rush" and then use the Rush medals to Zenkai awaken the unit you want. It takes 1 and half a month to fully Zenkai a unit from 0 so it's always good to complete the missions when the Zenkai is first released
