My game features a pair of "duelist" characters so that works out as something of a gateway; highly mobile, high AC/Reflex strikers, forced movement powers, and with a few ways to access surges of their own volition. I wouldn't recommend the trope without that role as the featured player as they are both naturally mobile and deploy their payload without help/synergy requirements. If you can pull it off without that role specifically but with those tactical values (natural mobility, surge access, and independent damage deployment), that would work too.
I've done it a few times, posing those PCs against an Elite Skirmisher (for the same reasons as the PC) 1 level below them. A large arena with patches of hindering and difficult terrain, areas of partial concealment, clearly conveyed terrain powers and hazards to interact with and force the enemy into has been key. I playtested the fights beforehand to ensure these features were functional.
One final thing I did the second time around was use a series of scribed encounter cards specific to the arena that the player drew at the end of the round. These would do something like a gust of wind shifts the battlefield, stray arrow from the other skirmish, random forest minion creature appears and attacks, lightning strike shattering a tree limb, cloudburst causing partial concealment for 1 round, waterfall obstruction, deep water, slippery rocks etc. That helped to promote dynamism but wasn't mandatory so long as the other things were in play.
As far as the killstealing goes, one arena was on the ramparts/gatehouse of a stronghold with the other PCs (and their 2 companion characters) fighting in the courtyard. The second was in a forest, at the base of a waterfall with the PCs (and their 2 companion characters) divided by a switchback, second tier of the raging waterfall, but within eyeshot, fighting swarms. In both scenarios, they had their own fights to resolve that tested them to their limits. Further, one duel arena had a lot of obstruction from the other PCs while the other had a lot of concealment. One of the group fights ended just (1 round) before the duel ended but they didn't attempt to intervene as they knew the drill (and it would have taken a round or more to access the duel arena). I guess "knowing the drill" is key there. That, of course, will vary with group!