Well, I used "Lari" but I'm thinking you should try something more original.. Um..... SoulRed? I was thinking SoulRed, because Latias and Latios and use the Soul Orb, and Latias is red, and it would be a new take on the name of the game your playing (SoulSilver). Meh, that's just me. You should really take a good look at your Pokemon, and study it. Look for it's colors, if a certain item only works on it, any abnormalities in it's shape, and the Pokemon species name.
How about Silver Angel
gardian angel (latias and latios are the giardians of this town someplace)