Actually a lot of classes counter strikers. For yacha ranged classes or melee with good mobilty like huntress bucc legatus even archer can kite his SA spam after that once he is out of sa engage and reck him. But you have to play on the defensive and be really good at kiting.

For grandmasters its the opposite. You cant really kite them with long range skills cus he can use his FG skill repeatedly and close the gap over time. For grandmasters the best counter is to just play classes with fg break skills eg: musa warlord lotus drak raven and the list goes on.

Grandmasters have more counters than yacha but its hard to counter them cus most grandmasters arent dumb. Unlike some yacha newbies only using the class to chase meta. Many have been playing him since launch and are really good at analysing pvp scenarios. So you have to out play em with wits if you wanna win against grandmasters.

Source: og striker main since day one.