If you meant wild Pokemon, in Black 2 no wild Pokemon has ever been 60+ other than those in shaking grass, dark grass, rippling water, Super Rod and Smoke clouds. Other than legendaries that is.
Pokemon that are above level 60 are:
10. Dragonspiral Tower Pokemon (in dark grass outside)
11. Pinwheel Forest (in dark grass)
12. P2 Laboratory (finshing on rippling spots can go as high as lvl 70)
16. Route 23 (Rippling spots)
... and many more.
Here are some major trainers who have 60+ level Pokemon though:
- Cilan, Chilli and Cress
- Bianca (after game sync)
- Cheren (after game sync)
- Shadow Triad (at Icirrus after beating game)
- GAMEFREAK Nishino
- GAMEFREAK Morimoto
- N (the Pokemon trainer)
- The Champion and the Elite four (in challenge mode as well as rematch)
See more information on them here.
Many trainers from the Post-game have level 60+ Pokemon, it gets commoner as you progress. further and further South of Unova.
Feel free to add to this, I might be missing a lot for all you know.
Hope I helped!