It would help to do some ID:
Japanese Iris have a central rib on each leaf (less than 1 inch wide) and the leaves are blue-green with a whitish haze.
Louisiana Iris have taller leaves that are yellow green, 1 inch wide or more with no ribs.
Siberian iris are similar in color to Japanese, more narrow (1/2" or less).
Other water iris include pseudacorus (similar to Louisiana), versicolor, lavigata...

IF your Iris went dormant this winter (all leaves died off) then it should be OK to move even if it started growth. In general the best time to move Iris is in the Fall after they have finished blooming. It is also OK to move them in early Spring, but there will be some root loss that will slow down growth. Any blooms are already "set" inside the rhizomes from last years growth.
Plants grown in pots in a pond are not fussy about drainage (duh) so any soil is OK, potting soil being the worst choice as it floats. Use Osmocote or other slow release tabs under the sol in the pot.

Hi chadinlg, thanks for your help. I'll do more research to see if I can find out what kind I have. I'll have a look tomorrow to see if any of your descriptions resemble mine.
During the winter, I could see green leaves but they have grown taller now and are beginning to look like a fan.

I'm going to take it out of the ground and plant it up for the pond to see what happens. I bought a pond basket today at the nursery. The nursery clerk told me to put some pea gravel in the bottom, add some soil, plant the iris's, and cover with more pea gravel. I hope that is right? I wonder how the soil is going to stay inside the basket which has tiny holes in it. Thank you for telling me about adding Osmocote etc. or I wouldn't have thought of that.
Thanks again for helping me with this.

if it's a variety if iris that likes to be in a bog (which i would assume from the fact that it was growing in a pond, presumably wet all the time) it may not bloom if not wet fairly frequently. my neighbor has some kind of swamp iris and the ones not grown in the pond don't bloom, they just leaf.