I've heard the term "T1" thrown around multiple times around here, but I'm unsure exactly what T1 entails. Could someone enlighten me? Preferably with a TL;DR version if at all applicable?

Additionally, I need a sparring partner to test a character concept out that I've yet to see demonstrated in the Arena section: fighting as a four-legged creature. Either this character approach doesn't work at all whatsoever when dealing with super-powered bipeds, it's banned due to the rules and regulations that pertain to proper Arena combat or it's merely never crossed the mind of anyone until now.

Short answer is T1 is one of the original forms of textual combat. There is a long complex history going back to 1999. T1 and variants of the ruleset are the accepted format on 'serious' dueling communities. Learn T1and you can pretty much fight anywhere.