Sorry, your 200-watt amp isn't going to keep up with your guitarist's 50-watt Marshall stack.
Funny, because it's had no problems competing with my guitarists 100 Watt Marshall stack.
Or my other bassists Ampeg, and GK stacks.
Or two guitarists 100 Watt stacks.
Or all of the above, plus keyboards, and samples, and some pretty heavy hitting drummers.
If you're playing too loudly, the vocals, and drum overheads, are going to be a disaster.