Sigh .. Winter, mate, I gave you a lot more information than that but it looks like you've forgotten again... here's another reminder for you why Escavalier is one of the ideal Pokemon to use against Radomus.
1) Enormous 135 base Attack means that at that level it can one shot almost every Pokemon it can hit super effectively with some investment or a Swords Dance boost (which it learns naturally!)
2) STAB Bug moves hit 5/6 of his Pokemon super effectively. (X-Scissor or Megahorn are your best options but the latter needs breeding and a Link Stone)
NOTE: 2 of those are 4x SE hits!
3) STAB Steel moves mean you have 2 super effective options against his ace, Gardevoir.
4) If you're willing to invest in breeding a little bit, you can get a Dark coverage move in Knock Off which is a super effective move against his only Pokemon that resists your Bug type STAB.
NOTE: This means you have an SE move to hit every Pokemon on his team.
5) Finally (but actually the most important point) Escavalier has a base Speed of 20, which makes it slower than every Pokemon on Radomus's team.. which means that Escavalier is a better user of Trick Room than Radomus's entire Trick Room team!
If you've still forgotten where to get it, let me remind you:
1) In Spinel Town, there is a certain ... "bug maniac", let's say. He is willing to trade you Shelmet for Karrablast and vice versa, allowing you to get an Escavalier by trading him a Shelmet.
1a) If memory serves, Shelmet can be found on Azurine Island, so grab one there and trade it away in Spinel Town.
2) If you're looking to breed one and use a Link Stone to evolve it (Megahorn and Knock Off are available this way, but not both) then you'll need to get a Karrablast and those can be found in Tanzan Cove and Chrysolia Forest iirc.
So there you have it. The cavalry is here.