For even the lowest level competitions, you'd need to at the very least be able to skate on one foot comfortably and do crossovers. For ice dance, the lowest level possible would be the ability to do at least the compulsory dances of the Dutch Waltz and Canasta Tango as a solo skater. And while these involve only forward skating, they require one foot glides on outside and inside edges, progressives (ice dance term for crossovers), stroking into one foot skating, and in the tango, chasses, which are a smooth move from one foot to the other sliding the free foot forward. Partnered skating requires more skills and is frequently done at higher levels although there are partnered compulsory dances. However, in those, both skaters must be able to perform the skills completely - you can't have one skater doing the moves and pulling the other skater along, you have to match each other in skills and and presentation.