Walking Wake and Iron Leaves are 5 star raids, which means they're not too difficult (7 star is the highest difficulty).
The raid bosses are level 75, so you probably want to be around there or higher if possible. Joining random groups online should help as well, since a lot of the online player base will be using level 100s and can carry you through it.
For raids you generally want a bulkier Pokemon because surviving is more important than doing the most damage. Each death reduces the timer, and you lose the raid when the timer runs out.
These Pokemon are solid counters for each:
Walking Wake: Clodsire (Water Absorb), Miraidon, Iron Hands, Iron Leaves
Iron Leaves: Gholdengo, Kingambit, Scizor, Skeledirge