If we take BV for army building off the table and look at 1 on 1, be it a Clan trail, Solaris bout or two isolated mechs, it comes down to allot of things. Clans have a clear advantage ton per ton (why IS strength has been numbers) so you really need to play towards individual mechs strengths on a particular battlefield.
Personally, I tried using terrain to my advantage to negate Clans range advantage. Clanners avoid Melee a tried to adhere to their dueling rules to gain honor so playing dirty usually works; hiding in wait like a ambush predator, using thunder mines, smoke and infernos, getting in close for melee, ect. This means it comes down to the player/Mechwarrior as much as the machine, if not more so. After that, it comes down to what will help you win.
Mechs that won IS vs Clan in my personal games;
Thunderbolt- Flexable and resilient, it doesn't have that knock down fire power but it has the durability to survive hits from clan weapons from Clan mechs around the same weight category. Took out a Hellbringer in a TDR-9SE, the jump jets where enough to allow me to get around building to help negate the Hellbringer's speed. A Summoner took out Thunderbolt after downing the Hellbringer but only after a lucky through armor critical to the engine (the RNG giveth, the RNG taketh away)
Flashman FLS-7K- a tough little guy often overlooked. It can be out flanked easily by the faster clan machines but like the Thunderbolt, it can take the hits long enough to make fair bit of damage in return. Some may prefer the Grasshopper instead just for the Jump Jets
Penetrator- Fellow forum mebers get really hung up on the mech having AMS ammo in the torso and seem to forget the Penetrator is still a jumping heaving with considerable firepower. As before; wait for an opening, jump in than jump out. Your opponent is faster but unless you are facing another jumping mech, you just need to bid your time befor trading shots.
Axman- You do not use this mech in a fair fight, you use this mech as if you are Jason Voorhees in a slasher movie. You wait in hiding (or even run away) until you have the opportunity to pump in close to use that AC/20. If you knock the mech down, then you keep using that AC/20 and add melee. If the mech is still standing, jump away until you next chance. The same can be said for the Ti Ts'ang only it has the speed to match most Clan heavies.
BlackKnight- There is a reason why this mech is almost always the center fold for the ComGuard. I honestly went full Leero Jenkins in this mech thinking it wasn't going to last but ended up soaking enough damage to give some in return. Some good rolls on my end defiantly helped as a number of bad piloting roles ended up killing a Timber Wolf before any of my weapons (slid on a street corner, crashed into a building and crited the engine) but at the end of the match, half of my Black Knight was still standing and the Timby was not. This was mostly RNG but worth mentioning. I have seen the Orion last to the end as well, surviving ammo explosion and out slugging more powerful mechs earning it's description in the fluff a durable command mech.
Battlemaster- I established that I'm a fan of the Thunderbolt, the Battlemaster is a bigger Thunderbolt with more armor and more armor means allot when you are going against bigger guns with more range. Play it like your heavies, wait for them to to get close so range is no longer the issue. The bonus for being a fat heavy mech is that those punches and kicks are going to hit that much more.
Berserker- Clanners don't like melee, this mech is design to run up to the opposing mech and start hitting it in the face with a hatchet and it has enough armor to keep hitting for awhile. Allot of people hate this mech for being the complete opposite of the Devastator/Nightstar/Gunslinger/Highlander but those mechs are meant to part of a gauss firing line, the Berserker is built to live up to its name and be more psychological than anything else... well, a 100 mech with a hatchet is going to make a satisfying sound when it hits but it's the fact you have a 100 ton mech that can close the distance so fast freaks out those not ready for it. Similar tactics as the Axman and Ti Ts'ang only once you have your opening, you don't stop. The Berserker has enough armor to take the damage when you play aggressively, you only need to play cat and mouse if your opponent has jump jets. Otherwise, push hem into a corner and keep swinging and kicking as long as you have armor.
