What to Buddy

Easy answer - Shuckle. Fear the rock bug.

Seriously, where are the holes in your teams? I've been walking Togepi. Sure, it didn't get a fairy fast move, but either Hidden Power: Flying (for STAB) or Hidden Power: Dragon (to take down Palkia) would be good. Glad I have like 40 FTM.

Do you have enough candy for Magnezone, Electivire, Yanmega, Weavile, Glaceon and Leafeon, and of course, Rhyperior and Mamoswine? If not, that will tell you what you need to walk the most. And a lot of people dismiss how useful Alolan Eggy can be, with double resistance to plant and water, and a great Bullet Seed/Solar Beam attack for raids, or /Seed Bomb for gym clearing.

Look at what your friends are walking. But in my area, that wouldn't help much because people buddy to show off. Torkoal, Relicanth, various shinies are buddied up. Lately, the 3rd stage evolutions of the Gen4 stuff. Not much help there.

Where are you weakest - work on that to shore it up. Or build on your strengths.

Walk whatever you need candy for.

I wouldn’t continue walking Tyranitar as we’re getting competitive Rock and Dark types. Bagon would be solid if you’re lacking candies. Community day is possible, but who knows when. Dratini could also be decent but Dragonite will likely be outclassed by Garchomp so I wouldn’t recommend investing in another one if you already have some. Giratina, Dialga and Palkia are also around the corner.

There’s also gen 4 prep. Magnetite, Togepi, Swinub, etc.

I need a lot of Dratini candy. Actually I don't need it, but I wish I had 600-700 more

Shinx.

Depending on your local gym scene, Chansey may be a great buddy choice.

I've been walking Rayquaza for 300 km and it feels the right thing.

I would not walk for Bagon or Larvitar candy. Dragonite will be a good attacker against Giratina and Palkia, but depends on how many Dratini you have banked. If you could choose between Gible and Dratini, Gible would always be the correct answer because Garchomp is a better pokemon, being also the top non-legendary ground and counter to Heatran.

The crossgen evos are a good alternative right now to walking Dratini, but which one to walk depends on how much candy you have for them already.

Personally I'm good with every crossgen evo and all old meta-relevant species, so I swapped to Shinx for the dex entry. Looking forward to Gible, which I foresee staying as my buddy for months.

I'm walking a Shinx since I'm pretty content with my attackers and want to focus on the dex entries now. Ask yourself what you actively need and go with that. If you can't think of anything then pick a fun buddy.

I walk my Dratini to get my first Dragonite. Recently got back to the game after leaving very shortly after launch