In your blender, place chipotles, shallot, garlic, orange juice, vinegar, oregano, chili powder, and salt. Liquify.
Add marinade to large resealable bag along with the pork. Marinade overnight.
Place grill over high heat. Slice pineapple into 1/2" rings. Grill pork for 3-4 minutes a side or until charred. Grill pineapple for 1 minute a side or until just marked. Do the same with the corn tortillas. Chop pork and pineapple, serve on tortillas adorned with the onion, lime, jalapenos, and cilantro.