Image choice: For GNS3, people commonly use IOS/IOS‑XE images that support the switch feature set. Use a stable image that matches the features you need (VLANs, SVI, EtherChannel, multilayer switching, routing protocols). Avoid images built for platforms GNS3 doesn’t emulate.
To legally download Cisco switch images for GNS3, you have two primary options: CiscoIOS Images for GNS3 - Cisco Community cisco 4500 switch ios download for gns3
To make a router act like a Cisco 4500 switch, you must add a switching module (NM-16ESW). Image choice: For GNS3, people commonly use IOS/IOS‑XE