I've been trying to catch a Mukrow to help me beat Morty. But is it only for members or can you find it on route 33 in johto?

--Moved to proper place--

Murkrow is membership-only on that specific route, but you don't need membership to catch it in game. There are several other routes in game where Murkrow will spawn for non-members, and Murkrow is also obtainable via headbutt on certain routes.

 

If you're having trouble finding Murkrow, you can instead search for Houndour, another Dark type Pokemon. Houndour spawns at night on Route 36, no membership required. You can also beat Morty using a level 40+ Rattata with Sucker Punch, or you can bring Normal types with sleep-inducing moves on your team. I used a Stantler with Hypnosis - Morty's Ghost types had no moves to damage my Stantler other than Sucker Punch, so I put them to sleep and switched into an attacker while they were asleep.

 

Good luck!