A bit new here, but I came up with a moveset I'm feeling rather comfortable with.
Sawsbuck @ Life Orb
Ability: Serene Grace
EVs: 252 Atk/252 Spe/4 SpA
Naive Nature
- Nature Power (Tri Attack)
- Horn Leech
- Jump Kick
- Wild Charge/Bounce/Shadow Ball
Behold, MixBuck. Though Sawsbuck lost access to Earthquake this generation (with the changes to Nature Power), it gained a new toy in the form of a Serene Grace-boosted Tri Attack. Despite the deer's middling 60 base Special Attack, having a whopping 40% chance to either burn, paralyze, or freeze your opponent is no joke, and it finally allows Serene Grace to finally be of use to the seasonal florafauna.
Barring its pre-evolution, only two other Pokémon have access to a grace-boosted Tri Attack: Shaymin-Sky and Togekiss. Both have a higher base Special Attack than Sawsbuck, but lack STAB on Tri Attack (the latter due to its changed typing this generation) and generally have access to better moves. For Sawsbuck, the combination of STAB and Life Orb brings Tri Attack's power to more acceptable levels, and its respectable 95 base Speed lets it fire off Tri Attack more easily than Togekiss.
Horn Leech is used for physical STAB and increased survivability, and works great in tandem with Life Orb. Jump Kick can dent Steel-types considerably, and also functions as a substitute for the long-gone NP Earthquake.
The last slot is for additional coverage and/or status infliction. Wild Charge nails Flying-types hard, though the combined recoil of Wild Charge and Life Orb may quickly wear down Sawsbuck, even with access to Horn Leech. Bounce gives Sawsbuck a chance to cripple the majority of resistant switch-ins with its whopping 60% chance of paralysis, though its low PP, shaky accuracy, and unreliability against Protect users may discourage its use in favor of other more reliable moves. Shadow Ball prevents Sawsbuck from being completely walled by Ghost-types, and the 40% chance for a Special Defense drop can even let Sawsbuck hit non-Ghost-types harder with Tri Attack.
Water-types such as Slowking, Jellicent and Rotom-W maker excellent partners for Sawsbuck, able to switch in on many of Sawsbuck's weaknesses, and either set up against crippled opponents who switch out, or hitting hard with Hex against those who stay in.