I guess I'll give you some help too.
It's best you ditch Swanna for another Water-type like Starmie, which outclasses it by a lot thanks to better stats and movepool. A good Starmie moveset should be made out of Ice Beam, Thunderbolt, Surf and Psychic. Also, go for Natural Cure over Illuminate.
Thunder and Blizzard have terrible accuracy outside of rain and hail respectively, and Tyranitar has a higher Attack stat so give it more physical attacks.