how strong is Tika compared to a normal pony?
Depends on how you compare.
She does have more physical strength for some things, and takes a lot of hits to get down. Even applejack would have a hard time kicking her back. But Tika wouldn’t have the right build to buck apples, despite having enough strength to kick over a tree if she knew how. Or would bother trying.
Despite being partly equine her attack instincts isn’t in rearing or kicking like most ponies would, her attack technique of choice focuses on her bite and tail. The tail is quite sturdy and can smash things apart even if she didn’t mean to and is an active tool to slam an opponent if they try an attack behind.
Her jaws are strong enough to bite through most materials, she can crunch bones and swallow anything they her unhinged jaws can fit. When bored she chews on the bars in her cage and leaves plenty a bite mark.
But her jaws are at the same time pretty weak. She can crunch down on anything, but she cannot open her mouth or unhinged her jaws of you tie them up or managed other kinds of holds around her muzzle. Kinda like a crocodile. The focus on the jaw muscles are to close and lock the jaws. Not on opening them.
This answer might be a bit over the place though.