The left and right side are typically different due to the throttle tube - but most grips are sold in pairs that take this into consideration, and most of the small bikes share common sizes. Both of my Hondas, the Suzuki, and the Husaberg all use the same size grips (the BMW is the only one that is different).
Not knowing what bars you have, it's impossible to say exactly what you need. But chances are that any decent bike shop will stock something that will fit. Just cut the old grips off and measure the OD of the bar on the left side, and the OD of the throttle tube on the right, then measure how wide the existing grips are. Then just match those measurements up to what is on the package at your local moto shop.
If you have heated grips (not likely on the XT225 - but like I said, it's impossible to say without seeing it), you may have a harder time finding grips.