Well, Ralts evolves into one of two crazy damn sweeper Pokemon. Arguably the best psychic type in the game.
But just because it’s not alolan form, doesn’t mean it’s good to receive. Slugma Is a cool one to send. Could also catch a bunch of Machokes, Boldores, Phantumps, etc. Things that evolve on trades are really neat to send. Those are harder to get, and significantly more helpful than a normal type rat.
I mean, you do you, but sending a ratticate doesn’t feel much different than sending a magikarp. Except magikarp evolves into gyarados, so I dunno how to equate those.
Could also recommend breeding the Pokemon you can get from the Island Scan feature. A lot of the original starters come from that, some cool stuff like Axew, Gothita, Togekiss, etc.