You can add a delay to every action (or at least to slower actions), giving you a natural opportunity to evade it (provided you have enough time).
Say you are going to act next in 5 ticks of game time, and your opponent begins an attack that takes 6 ticks to land. Your turn will come up before the attack connects, letting you either move out of the way of the attack or perform a guarding action. Hitting someone is then a matter of either timing your attack right so they don't have time to evade it, or positioning yourself such that they cannot physically move to evade it.
Then like a fighting game, you can have different amounts of hit/block stun on moves, or punish someone for missing an attack provided you can move and attack while they are recovering from missing their attack.
This would work best in a team based game, otherwise it would be too easy to just pick the optimal move at all times and avoid everything. You'd also want area of effect and other such wide angle attacks to limit evasion and be able to be used to position your opponent where you want them. Same with attacks that push your opponent around, being able to shove a blocking opponent into the path of another of your character's attacks would make for an interesting mechanic.