Nah, you want Lum Berry. Being forced to Rest whenever you are status'd is really annoying, while Lum Berry just cures it. Notably, you will get status'd when you switch into say Rotom-W (who is one of the more notable things Trevenant beats), and wouldn't you rather be able to attack it / status it immediately instead of Resting? Most of the time, the Lum Berry will be back by the time you Rest, and even if it does not, it's not the end of the world. Trevenant is a neat counter to all the bulky Water-types that rely on Scald, but using Chesto Rest makes it worse at that objective, among other things.
Lum berry has its uses, you don't need to be resting immediately after being inflicted by the status especialy against toxic as the first two ticks of dmg are laughable. Personally in my testing I have found sitrus to be far better than RestoChesto/Lum simply because sitrus is 100% passive while also freeing up a space for another move, and I have been able to stall even while burned, toxic is another story, but tbh you run protect in pretty much every set so you can scout for it if its not an immediate threat from say a toxic orb gliscor were you know they run toxic. I have tested many sets both lum chest and sitrus variants and have found these to be the best among the two.
This set has yet to fail me. Its an amazing mixed wall and always surprises people when they switch into there special attackers thinking they will be doing more dmg. More info on this set in post #183
Trevenant @ Sitrus Berry
Ability: Harvest
EVs: 84HP/252Def/172SpD
Impish Nature
- Rock Slide
- Wil-O-Wisp
- Leech Seed
- Protect
Problems this set has over Lum/Chesto
-Status (Can be resolved by using a poke with Heal Bell/Aromatherapy, or you can simply predict/scout with protect and proceed to switch out)
Trevenant @ Chesto Berry
Ability: Harvest
EVs: 252HP/252Def/4SpD or 252HP/4Def/252SpD
Impish/Careful Nature
- Rest
- Curse/Wil-O-Wisp/Toxic
- Shadow Claw/Horn Leech/Rock Slide/Wil-O-Wisp
- Protect/Curse/Leech Seed
Curse is a must in this set as you lack the sufficient stall dmg Burn/Leech gives you unless you choose to give up either your protect or atk.
Problems this set has over sitrus.
-Lack of Passive healing through sitrus.
-Need to use up a turn to heal. (Not the most reliable on a very slow pokemon with lack of natural bulk aside from its typing)
-Only 3 Moves to select from. (Rest is a requirement)
-Curse is incredibly risky and hard to set up as trevenant isn't the bulkiest of pokes. (again lack of sitrus makes this even harder 75%HP vs 50%HP after curse)
-Anything that can 2HKO will still 2HKO you, as resting is only delaying the inevitable.
-Is not viable as a mixed tank. (Through testing passive sitrus seems to make a huge difference)