My Ivysaur in pokemon Yellow.
It was level like 28 or something close, not 30s, but high twenties. I lost every pokemon to Givoanni, so I sent him out. EVERY attack of Giovanni's missed and all of my solarbeams connected, winning me the match. That thing grew like ten levels o.O
But from any other game it would have to be my Swampert from Emerald. It swept the elite four, no revives or NUTHIN, and won me 14 battles in Battle Tower undefeated. It was shiny, had no IVs or EVs 'cause i didnt know what those were back in the day...
OMG funny/depressing story about shinies. I was testing out my camera for a recorded battle so I went and played through a bit of the beginning of platinum. The chimchar I picked was SHINY!!! >_> And of course I couldn't save so... grrr!!!
OH EM GEE!!!
GS REMAKES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*Trys to look cool*
Not like I'm... excited or something