Tamiya plug has been the standard plug for RC cars made by Tamiya, so its quite ubiquitous by now. Tokyo Marui adopted it for its airsoft guns since most batteries that are made for RC cars and compatible with airsoft have Tamiya plug also, so its very convenient.
Unfortunately, it has a 15 amps limit, which is usually the normal AEG setup in the Philippines, so the plug usually heats up after use, and gradually degrades the connection and its efficiency.
Good thing is, Deans plug is also becoming the norm now, and its relatively cheap (100php for a pair) to replace the Tamiya plug. The Deans is rated to handle upto 50 amps+, but generally depends if its original or a knock-off. But 30 amps is generally a safe number for it to handle.