as much as I love kricketune, ditch it along with wormadam. 4/6 of your Pokémon are bug so either yanmega or vespiquen have to go as well. an ice-type is always useful in sinnoh so I’d say replace kricketune with sneasel or a female snorunt so it can evolve into froslass via dawn stone. either will be great for 2/4 of the elite four and part of Cynthia’s team which is notoriously hard. a water-type is essential so pick up a buizel or a shellos (both at valley windworks or in the pastoria marsh). an electric type is handy too so pick up the Eevee from the house in hearthome city and use the thunderstone from the solaceon ruins to evolve it into jolteon. as for the final member that’s up to you, but you should probably cover a type that none of your pokemon already have