BASIC had great facilities for both graphics and (matching the hardware of that era). Various simple primitives like LINE and CIRCLE baked into the language itself, the PLAY statement, ON PEN for light pens and ON STRIG for joysticks. There were quite a few video games for the likes of C64 and ZX Spectrum written in BASIC, usually with machine code snippets for perf-critical stuff.

Depends on the version of BASIC. The BASIC 2.0 in the C64 didn't have those things, but 7.0 in the C128 had graphic and sound commands. Unfortunately, the C128's near-100% compatibility with the C64 meant that very few games were written to take advantage of its new abilities. It made more sense to keep making games for the C64 and its much bigger market.