Can't find any engines on the Bachman web site or anybody else selling them. Looking for the longer engines that are powerful with dcc and sound.
Steam? Diesel?
If steam, I can offer the following points.
Bachmann has the USRA Pacific and Mikado available right now from retailers. However, the new ones right now don't come installed DCC/sound decoders. Some of the road names in the last run did, and they may still be around at various outlets.
Bachmann used to offer several other Spectrum series locomotives larger than those, and eBay is always rich with them if you look for them. The light and heavy mountains, the light 2-10-2, there was even a 2-6-6-2 at one point. However, the greater majority of these are going to be DC only locomotives, and if you want a big mama Jama engine, you're probably going to have to get accustomed to the idea of getting aftermarket DCC and sound into them.
I could be wrong of course, but the nature of your question makes me believe that you are a beginner in Model Railroading. I need to ask the question, what is the minimum radius curve on your layout? Because even though all of the engines listed above will somehow get through an 18 inch radius curve, they will all look ridiculous on it hanging over front and back, not to mention clearance problems with items close to the outside of the curve.
Plus, even though some of those engines may be called "DCC ready," they really are not, they require selection of the right speaker, installing the speaker so it doesn't rattle, soldering the decoder wires to the speaker, and making sure that the plug for the decoder into the motherboard is the right plug, they evolved over time and some of these early engines may not have the right plug for the modern decoder. In other words, you may want to engage a professional to do this work for you. They aren't cheap, but your engine comes back operating correctly without mistakes that beginners can make that can damage the decoder or the locomotive.
I'm sorry if I seem like I'm throwing a wet blanket over what you want, but those are the facts about these older engines and trying to get them up-to-date.
Just wondering if you are in the UK, as I believe Mainline is a UK brand. This is the North American Bachmann site, and if you are looking for British style locomotives you aren't going to find them here (Thomas excepted.)